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1 19-6250; rev 1; 7/12 ordering information appears at end of data sheet. typical application circuit appears at end of data sheet. for related parts and recommended products to use with this part, refer to www.maxim-ic.com/MAX2870.related . functional diagram general description the MAX2870 is an ultra-wideband phase-locked loop (pll) with integrated voltage control oscillators (vcos) capable of operating in both integer-n and fractional-n modes. when combined with an external reference oscillator and loop filter, the MAX2870 is a high-performance frequency synthesizer capable of synthesizing frequencies from 23.5mhz to 6.0ghz while maintaining superior phase noise and spurious performance. the ultra-wide frequency range is achieved with the help of multiple integrated vcos covering 3000mhz to 6000mhz, and output dividers ranging from 1 to 128. the device also provides dual differential output drivers, which can be independently programmable to deliver -4dbm to +5dbm output power. both outputs can be muted by either software or hardware control. the MAX2870 is controlled by a 3-wire serial interface and is compatible with 1.8v control logic. the device is available in a lead-free, rohs-compliant, 5mm x 5mm, 32-pin tqfn package, and operates over an extended -40 n c to +85 n c temp erature ran ge. applications benefits and features s integer and fractional-n modes s manual or automatic vco selection s 3000mhz to 6000mhz fundamental vco s output binary buffers/dividers for extended frequency range ? 1/2 /4 /8/16/32 /64/128 ? 23.5mhz to 6000mhz s high-performance pfd ? 105mhz in integer-n mode ? 50mhz in fractional-n mode s reference frequency up to 200mhz s operates from +3.0v to +3.6v supply s dual programmable outputs ? -4dbm to +5dbm s analog and digital lock detect indicators s hardware and software shutdown control s compatible with 1.8v control logic wireless infrastructure test and measurement satellite communications wireless lans /catv military and aerospace pmar /lmar /public safety radio clock generation ref_in clk data le x2 mux mux divide-by-2 r counter integer frac main modulator modulus vco spi and registers div-by- 1 /2/ 4/ 8 mux div-by- 1 /2/ 4/ 8/ 16 mu x mu x lock detect charge pump mux_out ld cp_out cp_gnd tune rfouta_p rfoutb_p rfout_en rfouta_n rfoutb_n n counter MAX2870 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco evaluation kit available for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxims website at www.maxim-ic.com.
2 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco v cc_ to gnd_ ....................................................... -0.3v to +3.9v all other pins to gnd_ .............................. -0.3v to v cc_ + 0.3v continuous power dissipation (t a = +70 n c) tqfn-ep multilayer board (derate 34.5mw/ n c above +70 n c) ......................... 2758.6mw junction temperature ..................................................... +150 n c operating temperature range .......................... -40 n c to +85 n c storage temperature range ............................ -65 n c to +150 n c lead temperature (soldering, 10s) .............................. +300 n c soldering temperature (reflow) ....................................... +260 n c tqfn junction-to-ambient thermal resistance ( b ja ) .......... 29 n c/w junction-to-case thermal resistance ( b jc ) .................. 1.7 n c/w absolute maximum ratings note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four- layer board. for detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial . stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional opera - tion of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. package thermal characteristics (note 1) dc electrical characteristics (measured using MAX2870 ev kit. v cc_ = 3v to 3.6v, v gnd_ = 0v, f ref_in = 50mhz, f pfd = 25mhz, t a = -40 n c to +85 n c. typical values measured at v cc _ = 3.3v; t a = +25 n c; register settings 00780000,20000141,01005e42,00000013,610f423c,01400005; unless otherwise noted.) (note 2) ac electrical characteristics (measured using MAX2870 ev kit. v cc_ = 3v to 3.6v, v gnd_ = 0v, f ref_in = 50mhz, f pfd = 25mhz, f rfout_ = 6000mhz, t a = -40 n c to +85 n c. typical values measured at v cc_ = 3.3v, t a = +25 n c, register settings 00780000,20000141,01005e42,00000 013,610f423c,01400005; unless otherwise noted.) (note 2) parameter conditions min typ max units supply voltage 3 3.3 3.6 v rfout_ current consumption i rfout_ , minimum output power, single channel 8.5 ma i rfout_ , maximum output power, single channel 25 29 supply current both channels enabled, maximum output power total, including rfout, both channel (note 3) 144 180 ma each output divide-by-2 10 15 i ccvco + i ccrf (note 3) 75 95 low-power sleep mode 1 parameter conditions min typ max units reference oscillator input (ref_in) ref_in input frequency range 10 200 mhz ref_in input sensitivity 0.7 v cc_ v pp ref_in input capacitance 2 pf ref_in input current -60 +60 f a phase detector phase detector frequency integer-n mode 105 mhz fractional-n mode 50
3 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco ac electrical characteristics (continued) (measured using MAX2870 ev kit. v cc_ = 3v to 3.6v, v gnd_ = 0v, f ref_in = 50mhz, f pfd = 25mhz, f rfout_ = 6000mhz, t a = -40 n c to +85 n c. typical values measured at v cc_ = 3.3v, t a = +25 n c, register settings 00780000,20000141,01005e42,00000 013,610f423c,01400005; unless otherwise noted.) (note 2) parameter conditions min typ max units charge pump sink/source current cp[3:0] = 1111, r set = 5.1k i 5.12 ma cp[3:0] = 0000, r set = 5.1k i 0.32 r set range 2.7 10 k i rf outputs fundamental frequency range 3000 6000 mhz divided frequency range with output dividers (1/2/4/8/16/32/64/128) 23.4375 6000 mhz vco sensitivity 100 mhz/v frequency pushing open loop 0.7 mhz/v frequency pulling open loop into 2:1 vswr 70 khz 2nd harmonic fundamental vco output 40 dbc 3rd harmonic fundamental vco output 34 dbc 2nd harmonic vco output divided-by-2 20 dbc 3rd harmonic vco output divided-by-2 21 dbc maximum output power f rfout_ = 3000mhz (note 4) 5 dbm minimum output power f rfout_ = 3000mhz (note 4) -4 dbm output power variation (note 4) -40 n c p t a p +85 n c 1.5 db 3v p v cc_ p 3.6v 0.2 muted output power (note 4) -31 dbm vco and frequency synthesizer noise vco phase noise (note 5) vco at 3000mhz 10khz offset -83.5 dbc/hz 100khz offset -111 1mhz offset -136 5mhz offset -149 vco at 4500mhz 10khz offset -75 100khz offset -104 1mhz offset -130 5mhz offset -145.5 vco at 6000mhz 10khz offset -71.5 100khz offset -100.5 1mhz offset -128.0 5mhz offset -143.5 in-band noise floor normalized (note 6) -223 dbc/hz 1/f noise normalized (note 7) -116 dbc/hz in-band phase noise (note 8) -95 dbc/hz integrated rms jitter (note 9) 0.45 ps spurious signals due to pfd frequency -87 dbc vco tune voltage 0.5 2.5 v
4 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco digital i/o characteristics (v cc_ = +3v to +3.6v, v gnd_ = 0v, t a = -40 n c to +85 n c. typical values at v cc _ = 3.3v, t a = +25 n c.) (note 2) spi timing characteristics (v cc_ = +3v to +3.6v, v gnd_ = 0v, t a = -40 n c to +85 n c. typical values at v cc _ = 3.3v, t a = +25 n c.) (note 2) note 2: production tested at t a = +25 n c. cold and hot are guaranteed by design and characterization. note 3: f refin = 40mhz, phase detector frequency = 40mhz, rf output = 3000mhz. register setting: 00780000,20000141,01005e42,00000013,610f43fc,01400005 note 4: measured single ended with 27nh to v cc_rf into 50 i load. power measured with single output enabled. unused output has 27nh to v cc_rf with 50 i termination. note 5: vco phase noise is measured open loop. note 6: measured at 100khz with 50mhz connor-winfield cwx813 tcxo with 500khz loop bandwidth. register setting: 803a0000,8000fff9,81005f42,f4000013,6384803c,001500005 note 7: 1/f noise contribution to the in-band phase noise is computed by using 1/fnoise + 10log(10khz/f offset ) + 20log(f rf /1ghz). register setting: 803a0000,8000fff9,81005f42,f4000013,6384803c,001500005 note 8: f refin = 50mhz; f pfd = 25mhz; offset frequency = 10khz; vco frequency = 4227mhz, output divide-by-2 enabled. rfout = 2113.5mhz; n = 169; loop bw = 40khz, cp[3:0] = 1111; integer mode. note 9: f refin = 50mhz; f pfd = 25mhz; vco frequency = 4400mhz, f rfout_ = 4400mhz; n = 176; loop bw = 40khz, cp[3:0] = 1111; integer mode. parameter conditions min typ max units serial interface inputs (clk, data, le, ce, rfout_en) input logic-level low 0.6 v input logic-level high v oh 1.5 v input current i ih /i il -1 +1 f a input capacitance 1 pf serial interface outputs (mux_out, ld) output logic-level low 0.3ma sink current 0.4 v output logic-level high 0.3ma source current v cc - 0.4 v output current level high 0.5 ma parameter symbol conditions min typ max units clk clock period t cp guaranteed by scl pulse-width low and high 50 ns clk pulse-width low t cl 25 ns clk pulse-width high t ch 25 ns le setup time t les 20 ns le hold time t leh 10 ns le minimum pulse-width high t lew 20 ns data setup time t ds 25 ns data hold time t dh 25 ns mux_out setup time t ms 10 ns mux_out hold time t mh 10 ns
5 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco typical operating characteristics (measured with MAX2870 ev kit. v cc_ = 3.3v, v gnd_ = 0v, f ref_in = 50mhz, t a = +25c, see the testing conditions table.) 3.0ghz vco open-loop phase noise vs. frequency max2780 toc01 frequency (khz) phase noise (dbc / hz) 10k 1k 100 10 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -160 1 100k 3.0ghz closed-loop phase noise vs. frequency max2780 toc04 frequency (khz) phase noise (dbc / hz) 10k 1k 100 10 -70 -170 1 100k -160 -150 -140 -130 -120 -110 -100 -90 -80 div1 div2 div4 div8 div16 div32 div64 div128 1k 100 10 1 10k max2780 toc07 frequency (khz) 904mhz integer-n mode phase noise and spur perfomance vs. frequency 0 -160 -140 -120 -100 -80 -60 -40 -20 phase noise (dbc / hz) spurs (dbc) 4.5ghz vco open-loop phase noise vs. frequency max2780 toc02 frequency (khz) phase noise (dbc / hz) 10k 1k 100 10 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -160 1 100k 4.5ghz closed-loop phase noise vs. frequency max2780 toc05 frequency (khz) phase noise (dbc / hz) 10k 1k 100 10 -70 -170 1 100k -160 -150 -140 -130 -120 -110 -100 -90 -80 div1 div2 div4 div8 div16 div32 div64 div128 1k 100 10 1 10k max2780 toc08 frequency (khz) 2687.5mhz integer-n mode phase noise and spur perfomance vs. frequency 0 -160 -140 -120 -100 -80 -60 -40 -20 phase noise (dbc / hz) spurs (dbc) 6.0ghz vco open-loop phase noise vs. frequency max2780 toc03 frequency (khz) phase noise (dbc / hz) 10k 1k 100 10 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -160 1 100k 6.0ghz closed-loop phase noise vs. frequency max2780 toc06 frequency (khz) phase noise (dbc / hz) 10k 1k 100 10 -70 -170 1 100k -160 -150 -140 -130 -120 -110 -100 -90 -80 div1 div2 div4 div8 div16 div32 div64 div128 1k 100 10 1 10k 2113.5mhz fractional-n phase noise (low-noise mode) vs. frequency max2780 toc09 frequency (khz) phase noise (dbc/hz) -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -170
6 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco typical operating characteristics (continued) (measured with MAX2870 ev kit. v cc_ = 3.3v, v gnd_ = 0v, f ref_in = 50mhz, t a = +25c, see the testing conditions table.) 1k 100 10 1 10k max2780 toc10 frequency (khz) phase noise (dbc/hz) -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -170 2113.5mhz fractional-n phase noise vs. frequency (low-spur mode) 1k 100 10 1 10k max2780 toc11 frequency (khz) phase noise (dbc/hz) -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -170 2679.4mhz fractional-n phase noise vs. frequency (low-noise mode) supply current vs. output power setting (one channel active, 3ghz) max2780 toc13 supply current (ma) 70 80 90 100 110 120 130 140 60 pwr setting 00 01 10 11 t a = +25c t a = +85c t a = -40c 1k 100 10 1 10k max2780 toc12 frequency (khz) phase noise (dbc/hz) -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -170 2679.4mhz fractional-n phase noise vs. frequency (low-spur mode) supply current vs. frequency (one channel active, maximum output power) max2780 toc14 frequency (mhz) supply current (ma) 1k 100 70 90 110 130 150 170 190 210 230 250 50 10 10k t a = +25c t a = +85c t a = -40c supply current vs. output power setting (two channels active) max2780 toc15 supply current (ma) 180 80 pwr setting 00 01 10 11 t a = +25c t a = +85c t a = -40c 90 100 110 120 130 140 150 160 170
7 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco typical operating characteristics (continued) (measured with MAX2870 ev kit. v cc_ = 3.3v, v gnd_ = 0v, f ref_in = 50mhz, t a = +25c, see the testing conditions table.) typical operating characteristics testing conditions table toc title f ref (mhz) f pfd (mhz) register settings (hex) loop filter bw (hz) MAX2870 ev kit component values comments c13 (f) r1 + r2 ( i ) c14 (f) r0 ( i ) c12 (f) 3.0ghz vco open-loop phase noise vs. frequency n/a n/a 80b40000, 80000141, 0000405a, xx00013, 648020fc, 00000005 vco bits set for 3ghz output, vas_shdn = 1 4.5ghz vco open-loop phase noise vs. frequency n/a n/a 80b40000, 80000141, 0000405a, xx00013 648020fc, 00000005 vco bits set for 4.5ghz output, vas_shdn = 1 6.0ghz vco open-loop phase noise vs. frequency n/a n/a 80b40000, 80000141 0000405a xx00013, 648020fc 00000005 vco bits set for 6.0ghz output, vas_shdn = 1 supply current vs. frequency (two channels active, maximum output power) max2780 toc16 frequency (mhz) supply current (ma) 1k 100 120 140 160 180 200 220 240 260 280 300 100 10 10k t a = +25c t a = +85c t a = -40c pll lock vs. time max2780 toc17 time (s) frequency (ghz) 150 100 50 3.00 3.02 3.04 3.06 3.08 2.98 0 200 fastlock off fastlock on
8 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco typical operating characteristics testing conditions table toc title f ref (mhz) f pfd (mhz) register settings (hex) toc title MAX2870 ev kit component values comments c13 (f) r1 + r2 ( i ) c14 (f) r0 ( i ) c12 (f) 3.0ghz closed-loop phase noise vs. frequency 50 25 803c0000 80000141 00009e42, e8000013, 618160fc, 00400005 40k 0.1 f 120 0.012 f 250 820p 4.5ghz closed-loop phase noise vs. frequency 50 25 805a0000, 80000141, 00009e42, e8000013, 618160fc, 00400005 40k 0.1 f 120 0.012 f 250 820p 6.0ghz closed-loop phase noise vs. frequency 50 25 80780000, 0080000141, 00009e42, ea000013, 608c80fc, 00400005 40k 0.1 f 120 0.012 f 250 820p 904mhz integer-n mode phase noise and spur perfomance vs. frequency 40 0.8 82350000, 800007d1 e1065fc2, 2c000013 6020803c 00400005 16k 0.1 f 806 3300p 1201 470p 2687.5mhz integer-n phase noise and spur performance vs. frequency 40 0.5 94ff0000, 803207d1, 010a1e42, b00000a3, 6090803c, 00400005 5k 0.1 f 1000 6800p 300 0.01 f 2113.5mhz fractional-n phase noise (low-noise mode) vs. frequency 50 25 00548050, 400003e9, 81005fc2, e8000013, 609c80fc, 00400005 40k 0.1 f 120 0.012 f 250 820p 2113.5mhz fractional-n phase noise vs. frequency (low-spur mode) 50 25 00548050, 400003e9, e1005fc2, e8000013, 609c80fc, 00400005 40k 0.1 f 120 0.012 f 250 820p
9 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco typical operating characteristics testing conditions table toc title f ref (mhz) f pfd (mhz) register settings (hex) toc title MAX2870 ev kit component values comments c13 (f) r1 + r2 ( i ) c14 (f) r0 ( i ) c12 (f) 2679.4mhz fractional-n phase noise vs. frequency (low-noise mode) 50 25 00358160, 203207d1, 01005e42, b20000a3, 6010003c, 00400005 40k 0.1 f 120 0.012 f 250 820p 2679.4mhz fractional-n phase noise vs. frequency (low-spur mode) 25 00358160, 203207d1, 41005e42, b20000a3, 6010003c, 00400005 40k 0.1 f 120 0.012 f 250 820p supply current vs. output power setting (one channel active, 3ghz) 50 25 003c0000, 20000321, 01005e42, 00000013, 610f423c, 01400005, apwr swept from 00 to 11 supply current vs. frequency (one channel active, maximum output power) 50 25 003c0000, 20000321, 01005e42, 00000013, 610f423c, 01400005 n and f values changed for each frequency supply current vs. output power setting (two channels active) 50 25 003c0000, 20000321, 01005e42, 00000013, 610f43fc, 01400005 apwr and bpwr swept from 00 to 11 supply current vs. frequency (two channels active maximum output power) 50 25 003c0000, 20000321, 01005e42, 00000013, 610f43fc, 01400005 n and f values swept for each frequency pll lock vs. time 40 40 00250120, 20320141, 00004042, 000000a3, 0184023c, 01400005 40k 0.1 f 120 0.012 f 250 820p cdm changed from 00 to 01
10 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco pin description pin configuration pin name function 1 clk serial clock input. the data is latched into the 32-bit shift register on the rising edge of the clk line. 2 data serial data input. the serial data is loaded msb first. the 3 lsbs identify the register address. 3 le load enable input. when le goes high the data stored in the shift register is loaded into the appropriate latches. 4 ce chip enable. a logic-low powers the part down and the charge pump becomes high impedance. 5 sw fast-lock switch. connect to the loop filter when using the fast-lock mode. 6 v cc_cp power supply for charge pump. place decoupling capacitors as close as possible to the pin. 7 cp_out charge-pump output. connect to external loop filter input. 8 gnd_cp ground for charge-pump. connect to board ground, not to the paddle. 9 gnd_pll ground for pll. connect to main board ground plane, not to the paddle. 10 v cc_pll power supply for pll. place decoupling capacitors as close as possible to the pin. 11 gnd_rf ground for rf outputs. connect to board ground plane, not to the paddle. 12 rfouta_p open collector positive rf output a. connect to supply through rf choke or 50 i load. 13 rfouta_n open collector negative rf output a. connect to supply through rf choke or 50 i load. MAX2870 tqfn top view 29 30 28 27 12 11 13 data ce sw v cc_cp cp_out 14 clk bias_filt gnd_tune tune reg noise_filt gnd_vco 12 v cc_dig 45 67 23 24 22 20 19 18 ref_in mux_out rfoutb_p rfouta_n rfouta_p gnd_rf le rset 3 21 31 10 gnd_sd ep v cc_pll 32 9 v dd_sd gnd_pll + gnd_dig 26 15 rfoutb_n rfout_en 25 16 v cc_rf gnd_cp v cc_vco 8 17 ld
11 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco pin description (continued) pin name function 14 rfoutb_p open collector positive rf output b. connect to supply through rf choke or 50 i load. 15 rfoutb_n open collector negative rf output b. connect to supply through rf choke or 50 i load. 16 v cc_rf power supply for rf output and dividers. place decoupling capacitors as close as possible to the pin. 17 v cc_vco vco power supply. place decoupling capacitors to the analog ground plane. 18 gnd_vco ground for vco. connect to external paddle. 19 noise_filt vco noise decoupling. place a 1 f f capacitor to ground. 20 tune control input to the vco. connect to external loop filter. 21 gnd_tune ground for control input to the vco. connect to external paddle. 22 rset charge-pump current range input. connect an external resistor to ground to set the minimum cp current. i cp = 1.63/r set x (1 + cp) 23 bias_filt vco noise decoupling. place a 1 f f capacitor to ground. 24 reg reference voltage compensation. place a 1 f f capacitor to ground. 25 ld lock detect output. logic-high when locked, and logic-low when unlocked. see register description for more details (table 9). 26 rfout_en rf output enable. a logic-low disables the rf outputs. 27 gnd_dig ground for digital circuitry. connect to main board ground plane, not directly to the paddle. 28 v cc_dig power supply for digital circuitry. place decoupling capacitors as close as possible to pin. 29 ref_in reference frequency input. this is a high-impedance input with a nominal bias voltage of v cc_dig /2. ac-couple to reference signal. 30 mux_out multiplexed output and serial data out. see table 6. 31 gnd_sd ground for sigma-delta modulator. connect to main board ground plane, not directly to the paddle. 32 v cc_sd power supply for sigma-delta modulator. place decoupling capacitors as close as possible to the pin. ep exposed pad. connect to board ground.
12 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco detailed description 4-wire serial interface the MAX2870 serial interface contains five write-only and one read-only 32-bit registers. the 29 most-significant bits (msbs) are data, and the three least-significant bits (lsbs) are the register address. register data is loaded msb first through the 4-wire serial interface (spi). when le is logic-low, the logic level at data is shifted at the rising edge of clk. at the rising edge of le, the 29 data bits are latched into the register selected by the address bits. the user must program all register values after power-up. register programming order should be address 0x05, 0x04, 0x03, 0x02, 0x01, and 0x00. several bits are dou - ble buffered to update the settings at the same time. see the register descriptions for double buffered settings. regi ster 0x06 can be read back through mux_out. the user must set mux = 1100. to begin the read sequence, set le to logic-low, send 32 periods of clk, and set le to logic-high. while the clk is running, the data pin can be held at logic-high or logic-low for 29 clocks, but the last 3 bits must be 110 to indicate regis - ter 6. then finally, send 1 period of the clock. the msb of register 0x06 appears on the falling edge of the next clock and continues to shift out for the next 29 clock cycles (figure 2). after the lsb of register 0x06 has been read, the user can reset mux = 0000. power modes the ma x2870 can be put into low-power mode by set - ting shdn = 1 (register 2, bit 5) or by setting the ce pin to logic -low. figure 1. spi timing diagram figure 2. initiating readback le cl k 32 data 31 30 29 1 33 34 35 t ms t mh 36 don?t care mux_out le t dh t ds t cl t den t leh clk data t les t ch t cp t lew
13 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco reference input the reference input stage is configured as a cmos inverter with shunt resistance from input to output. in shutdown mode this input is set to high impedance to prevent loading of the reference source. the reference input signal path also includes optional x2 and 2 blocks. when the reference doubler is enabled (dbr = 1), the maximum reference input frequency is lim - ited to 100mhz. when the doubler is disabled, the refer - ence input frequency is limited to 200mhz. the minimum reference frequency is 10mhz. the minimum r counter divide ratio is 1, and the maximum divide ratio is 1023. int, frac, mod, and r counter relationship the phase-detector frequency is determined as follows: f pfd = f ref o [(1 + dbr)/(r x (1 + rdiv2))] f ref represe nts the external reference input frequency. dbr (register 2, bit 25) sets the f ref input frequency doubler mode (0 or 1). rdiv2 (register 2, bit 24) sets the f ref divide-by-2 mode (0 or 1). r (register 2, bits 23:14) is the value of the 10-bit programmable reference counter (1 to 1023). the maximum f pfd is 50mhz for frac-n mode and 105mhz for int-n mode. the r-divider can be held in reset when rst (register 2, bit 3) = 1. the vco frequency (f vco ), n, f, and m can be deter - mined based on desired rf output frequency (f rfouta ) as follows: set diva value property based on f rfouta and diva register table (register 4[22.20]) f vco = f rfouta x diva if bit fb = 1, (diva is not in pll feedback loop): (n + (f/m) = f vco/ f pfd if bit fb = 0, (diva is in pll feedback loop) and diva 16: (n + (f/m) = (f vco /f pfd )/diva if bit fb = 0, (diva is in pll feedback loop) and diva > 16: (n + (f/m) = (f vco / f pfd )/16 n is the value of the 16-bit n counter (16 to 65535), programmable through bits 30:15 of register 0. m is the fractional modulus value (2 to 4095), programmable through bits 14:3 of register 1. f is the fractional division value (0 to mod - 1), programmable through bits 14:3 of register 0. in frac-n mode, the minimum n value is 19 and maximum n value is 4091. the n counter is held in reset when rst = 1 (register 2, bit 3). diva is the rf output divider setting (0 to 7), programmable through bits 22:20 of register 4. the division ratio is set by 2 diva . the rf b output frequency is determined as follows: if bdiv = 0 (register 4, bit 9), f rfoutb = f rfouta . if bd iv = 1, f rfoutb = f vco . int-n/frac-n modes integer-n mode is selected by setting bit int = 1 (regis - ter 0, bit 31). when operating in integer-n mode, it is also necessary to set bit ldf (register 2, bit 8) to set the lock detect to integer-n mode. the devices frac-n mode is selected by setting bit int = 0 (register 0, bit 31). additionally, set bit ldf = 0 (register 2, bit 8) for frac-n lock-detect mode. if the device is in frac-n mode, it will remain in frac-n mode when fractional division value f = 0, which can result in unwanted spurs. to avoid this condition, the device can automatically switch to integer-n mode when f = 0 if the bit f01 = 1 (register 5, bit 24). phase detector and charge pump the devices charge-pump current is determined by the value of the resistor from pin rset to ground and the value of bits cp (register 2, bits 12:9) as follows: i cp = 1.63/r set x (1 + cp) to reduce spurious in frac-n mode, set charge-pump linearity bit cpl = 1 (register 1, bits 30:29). for int-n mode, set cpl = 0. for lower noise operation in int-n mode, set charge-pump output clamp bit cpoc = 1 (register 1, bit 31) to prevent leakage current onto the loop filter. for frac-n mode, set cpoc = 0. figure 3. reference input ref_in x2 divide-by-2 pfd r counter mux mux
14 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco the charge-pump output can be put into high-imped - ance mode when tri = 1 (register 2, bit 4). the output is in normal mode when tri = 0. the phase detector polarity can be changed if an active inverting loop filter topology is used. for noninverting loop filters, set pdp = 1 (register 2, bit 6). for inverting loop filters, set pdp = 0. mux_out and lock detect mux_out is a multipurpose test output for observing various internal functions of the MAX2870. mux_out can also be configured as serial data output. bits mux (register 2, bit 28:26) are used to select the desired mux_out signal (see table 6). lock detect can be monitored through the ld output by setting the ld bits (register 5, bits 23:22). for digital lock detect, set ld = 01. the digital lock detect is dependent on the mode of the synthesizer. in frac-n mode set ldf = 0, and in int-n mode set ldf = 1. to set the accuracy of the digital lock detect, see tables 1 and 2. analog lock detect can be set with ld = 10. in this mode, ld is an open-drain output and requires an external pullup resistor. fast-lock the device uses a fast-lock mode to decrease lock time. this mode requires that cp = 0000 (register 2, bits 12:9) and that the shunt resistive portion of the loop filter be segmented into two parts, where one resistor is 1/4th the total resistance, and the other resistor is 3/4th the total resistance. the larger resistor should be connected from ground to sw, and the smaller resistor from sw to the loop filter capacitor. when cdm = 01 (register 3, bits 16:15), fast-lock is active after the vas has completed. during fast-lock, the charge pump is increased to cp = 1111 and the shunt loop filter resistance is set to 1/4th the total resistance by changing pin sw from high imped - ance to ground. fast-lock deactivates after a timeout set by the user. this timeout is loop filter dependent, and is set by: t fast-lock = m x cdiv/f ref where m is the modulus setting and cdiv is the clock divider setting. the user must determine the cdiv setting based on their loop filter time constant. rfouta and rfoutb the device has dual differential open-collector rf out - puts that require an external rf choke 50 i resistor to supply for each output. each differential output can be independently enabled or disabled by setting bits rfa_en (register 4, bit 5) and rfb_en (register 4, bit 8). both outputs are also controlled by applying a logic-high (enabled) or logic-low (disabled) to pin rfout_en. the output power of each output can be individually controlled with apwr (register 4, bits 4:3) for rfouta and bpwr (register 4, bits 7:6) for rfoutb. the avail - able differential output power settings are from -4dbm to +5dbm, in 3db steps with 50 i pullup to supply. the available single-ended output power ranges from -4dbm to +5dbm in 3db steps with a rf choke to supply. across the entire frequency range different pullup elements (l or r) are required for optimal output power. if the output is used single ended, the unused output should be termi - nated in a corresponding load. table 2. int-n digital lock-detect settings table 1. frac-n digital lock-detect settings pfd frequency lds ldp locked up/down time skew (ns) number of locked cycles to set ld up/downtime skew to unset ld (ns) p 32mhz 0 0 10 5 15 p 32mhz 0 1 6 5 15 > 32mhz 1 x 4 5 4 pfd frequency lds ldp locked up/down time skew (ns) number of locked cycles to set ld up/downtime skew to unset ld (ns) p 32mhz 0 0 10 40 15 p 32mhz 0 1 6 40 15 > 32mhz 1 x 4 40 4
15 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco voltage-controlled oscillator the fun damental vco frequency of the device guarantees gap-free coverage from 3.0ghz to 6.0ghz using four individual vco core blocks with 16 sub-bands within each block. connect the output of the loop filter to the tune input. the tune input is used to control the vc o. tune adc a 3-bit adc is used to read the vco tuning voltage. the adc value can be read back by bits 22:20 in register 6. the adc uses the ranges shown in table 3. note that the digital or analog lock detect might still be valid when the tuning voltage is out of the compliance range. vco autoselect (vas) state machine an inter nal vco autoselect state machine is initiated when register 0 is programmed to automatically select the correct vco if bit vas_shdn = 0 (register 3, bit 25). if vas_shdn = 1, then the vco can be manually selected by bits vco. the state machine clock, f bs , must be set to 50khz. this is set by the bs bits. the formula for setting bs is: bs = f ref /50khz where f ref is the reference frequency. the bs (register 4, bits 19:12) value should be rounded to the nearest inte - ger. if the calculated bs is higher than 1023, then set bs = 1023. if f ref is lower than 50khz, then set bs = 1. the time needed to select the correct vco is 10/f bs . the retune (register 3, bit 24) bit is used to enable or disable the vas auto-retune function. should the 3-bit tune adc detect that the vco control voltage (v tune ) has drifted into the 000 or 111 state, the vas will initiate an auto-retune if retune = 1. if retune = 0, then this function is d isabled. phase shift mode after ac hieving lock, the phase of the rf output can be changed in increments of p/m x 360 n . the absolute phase cannot be determined, but it can be changed relative to the current phase. to change the phase, do the following: 1) achieve lock at the desired frequency. 2) set the increment of phase relative to the current phase by setting p = m x {desired_phase_change}/360 n . 3) enable the phase change by setting cdm = 10. 4) reset cdm = 00. low-spur mode the device offers three modes for the sigma-delta modu - lator. low-noise mode offers lower in-band noise at the expense of spurs. the spurs can be reduced by setting sdn = 10 (register 2, bits 30:29) or sdn = 11 for different modes of dithering. the user can determine which mode works best for their application. table 3. adc vco status adc vco status 000 out-of-lock, v tune < 0.5v 001 in-lock, 0.5v < v tune < 0.7v 010 in-lock, 0.7v < v tune < 1.3v 011 not used 100 not used 101 in-lock, 1.3v < v tune < 2.1v 110 in-lock, 2.1v < v tune < 2.5v 111 out-of-lock, v tune > 2.5v
16 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco register and bit descriptions the operating mode of the device is controlled by five on-chip registers. defaults are not guaranteed upon power-up and are provided for reference only. all reserved bits should only be written with default values. in low-power mode the register values are retained. table 4. register 0 (address: 000, default: 007d0000 hex ) table 5. register 1 (address: 001, default: 2000fff9 hex ) bit location bit id name definition 31 int int-n or frac-n mode control 0 = enables the fractional-n mode 1 = enables the integer-n mode the ldf bit must also be set to the appropriate mode. 30:15 n[15:0] integer division value sets integer part (n-divider) of the feedback divider factor. all integer values from 16 to 65,535 are allowed for integer mode. integer values from 19 to 4,091 are allowed for fractional mode. 14:3 frac[11:0] fractional division value sets fractional value: 000000000000 = 0 (see f0i bit description) 000000000001 = 1 ---- 111111111110 = 4094 111111111111 = 4095 2:0 addr[2:0] address bits register address bits bit location bit id name definition 31 cpoc cp output clamp sets charge-pump output clamp mode. 0 = disables clamping of the cp output when the cp is off 1 = enables the clamping of the cp output when the cp is off (improved integer-n in-band phase noise) 30:29 cpl[1:0] cp linearity sets cp linearity mode. 00 = disables the cp linearity mode (integer-n mode) 01 = enables the cp linearity mode (frac-n mode) 10 = reserved 11 = reserved 28:27 cpt[1:0] charge pump test sets charge-pump test modes. 00 = normal mode 01 = reserved 10 = force cp into source mode 11 = force cp into sink mode 26:15 p[11:0] phase value sets phase value. see the phase shift mode section. 000000000000 = 0 000000000001 = 1 (recommended) ----- 111111111111 = 4095
17 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco table 6. register 2 (address: 010, default: 00004042 hex ) table 5. register 1 (address: 001, default: 2000fff9 hex ) (continued) bit location bit id name definition 31 lds lock-detect speed lock-detect speed adjustment. 0 = f pfd p 32mhz 1 = f pfd > 32mhz 30:29 sdn[1:0] frac-n noise mode sets noise mode (see the low-spur mode section.) 00 = low-noise mode 01 = reserved 10 = low-spur mode 1 11 = low-spur mode 2 28:26 mux[3:0] mux_out configuration sets mux_out pin configuration (msb bit located register 05). 0000 = three-state output 0001 = d_vdd 0010 = d_gnd 0011 = r-divider output 0100 = n-divider output 0101 = analog lock detect 0110 = digital lock detect 0111:1011 = reserved 1100 = read register 06 mux_out is configured as serial data out. 1101:1111 = reserved 25 dbr reference doubler mode sets reference doubler mode. 0 = disable reference doubler 1 = enable reference doubler 24 rdiv2 reference div2 mode sets reference divider mode. 0 = disable reference divide-by-2 1 = enable reference divide-by-2 23:14 r[9:0] reference divider mode sets reference divide value (r). double buffered by register 0. 0000000000 = 0 (unused) 0000000001 = 1 ----- 1111111111 = 1023 bit location bit id name definition 14:3 m[11:0] modulus value (m) fractional modulus value used to program f vco . see the int, frac, mod, and r counter relationship section. double buffered by register 0. 000000000000 = unused 000000000001 = unused 000000000010 = 2 ----- 111111111111 = 4095 2:0 addr[2:0] address bits register address bits
18 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco table 6. register 2 (address: 010, default: 00004042 hex ) (continued) bit location bit id name definition 13 reg4db double buffer sets double buffer mode. 0 = disabled 1 = enabled 12:9 cp[3:0] charge-pump current sets charge-pump current in ma (r set = 5.1k i ). double buffered by register 0. 0000 = 0.32 0001 = 0.64 0010 = 0.96 0011 = 1.28 0100 = 1.60 0101 = 1.92 0110 = 2.24 0111 = 2.56 [icp = 1.63/rset x (1 + cp<3:0>)] 1000 = 2.88 1001 = 3.20 1010 = 3.52 1011 = 3.84 1100 = 4.16 1101 = 4.48 1110 = 4.80 1111 = 5.12 8 ldf lock-detect function sets lock-detect function. 0 = frac-n lock detect 1 = int-n lock detect 7 ldp lock-detect precision sets lock-detect precision. 0 = 10ns 1 = 6ns 6 pdp phase detector polarity sets phase detector polarity. 0 = negative (for use with inverting active loop filters) 1 = positive (for use with passive loop filers and noninverting active loop filters) 5 shdn power-down mode sets power-down mode. 0 = normal mode 1 = device shutdown 4 tri charge-pump three-state mode sets charge-pump three-state mode. 0 = disabled 1 = enabled 3 rst counter reset sets counter reset mode. 0 = normal operation 1 = r and n counters reset 2:0 addr address bits register address
19 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco table 7. register 3 (address: 011, default: 0000000b hex ) bit location bit id name definition 31:26 vco[5:0] vco manual selection of vco and vco sub-band when vas is disabled. 000000 = vco0 . 111111 = vco63 25 vas_shdn vas_shdn sets vas state machine mode. 0 = vas enabled 1 = vas disabled 24 retune retune sets vas response to temperature drift. 0 = vas auto-retune over temp disabled 1 = vas auto-retune over temp enabled 23:18 reserved reserved reserved. program to 000000. 17 reserved reserved reserved. program to 0. 16:15 cdm[1:0] clock divider mode sets clock divider mode. 00 = clock divider off 01 = fast-lock enabled 10 = phase mode 11 = reserved 14:3 cdiv[11:0] clock divider value sets 12-bit clock divider value. 000000000000 = unused 000000000001 = 1 000000000010 = 2 ----- 111111111111 = 4095 2:0 addr[2:0] address bits register address
20 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco table 8. register 4 (address: 100, default: 6180b23c hex ) bit location bit id name definition 31:26 reserved reserved reserved. program to 011000. 25:24 bs_msbs[1:0] band-select msbs band-select msbs. see bits [19:12]. 23 fb vco feedback mode sets vco to n counter feedback mode. 0 = divided 1 = fundamental 22:20 diva[2:0] rfout_ output divider mode sets rfout_ output divider mode. double buffered by register 0 when reg4db = 1. 000 = divide by 1, if 3000mhz f rfouta 6000mhz 001 = divide by 2, if 1500mhz f rfouta < 3000mhz 010 = divide by 4, if 750mhz f rfouta < 1500mhz 011 = divide by 8, if 375mhz f rfouta < 750mhz 100 = divide by 16, if 187.5mhz f rfouta < 375mhz 101 = divide by 32, if 93.75mhz f rfouta < 187.5mhz 110 = divide by 64, if 46.875mhz f rfouta < 93.75mhz 111 = divide by 128, if 23.5mhz f rfouta < 46.875mhz 19:12 bs[7:0] band select sets band select clock divider value. msb are located in bits [25:24]. 0000000000 = reserved 0000000001 =1 0000000010 = 2 ---- 1111111111 = 1023 11 reserved reserved reserved. program to 0. 10 reserved reserved reserved. program to 0. 9 bdiv rfoutb output path select sets rfoutb output path select. 0 = vco divided output 1 = vco fundamental frequency 8 rfb_en rfoutb output mode sets rfoutb output mode. 0 = disabled 1 = enabled 7:6 bpwr[1:0] rfoutb output power sets rfoutb single-ended output power. see the rfouta q and rfoutb q section. 00 = -4dbm 01 = -1dbm 10 = +2dbm 11 = +5dbm 5 rfa_en rfouta output mode sets rfouta output mode. 0 = disabled 1 = enabled 4:3 apwr[1:0] rfouta output power sets rfouta single-ended output power. see the rfouta q and rfoutb q section. 00 = -4dbm 01 = -1dbm 10 = +2dbm 11 = +5dbm 2:0 addr[2:0] register address register address
21 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco table 9. register 5 (address: 101, default: 00400005 hex ) table 10. register 6 (read-only register) bit location bit id name definition 31:25 reserved reserved reserved. program to 0000000. 24 f01 f01 sets integer mode for f = 0. 0 = if f[11:0] = 0, then fractional-n mode is set 1 = if f[11:0] = 0, then integer-n mode is auto set 23:22 ld[1:0] lock-detect pin function sets lock-detect pin function. 00 = low 01 = digital lock detect 10 = analog lock detect 11 = high 21:19 reserved reserved reserved. program to 000. 18 mux mux msb sets mode at mux_out pin (see register 2 [28:26]) 17:3 reserved reserved reserved 2:0 addr[2:0] register address register address bits bit location bit id name definition 31:24 reserved reserved 23 por power_on_ reset por readback status. 0 = por has been read back 1 = por has not been read back (registers at default) 22:20 adc[2:0] vtune_adc reads back the adc reading of the v tune (see the tune adc section) 19:9 reserved reserved 8:3 v[5:0] active vco reads back the current active vco. 000000 = vco0 111111 = vco63 2:0 addr[2:0] register address register address bits
22 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco typical application circuit for best performance generate three supplies using separate ldos. v cc_rf v cc_dig v cc_pll 12 34 56 78 v cc_dig ref_in mux_out ep 9 10 11 v dd_sd gnd_dig gnd_sd rfout_en 24 23 22 21 20 19 18 17 ld to gpio from gpio clk data le ce sw v cc_cp cp_out gnd_cp gnd_pll gnd_rf rfouta_p rfouta_n rfouta rfoutb rfoutb_p rfoutb_n v cc_rf v cc_vco spi interface v cc_pll v cc_pll v cc_rf v cc_pll v cc_rf v cc_dig v cc_rf v cc_dig gnd_vco gnd_tune rset noise_filt bias_filt reg tune 12 13 14 15 16 32 31 30 29 28 27 26 25 MAX2870 from gpio
23 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco ordering information + denotes a lead(pb)-free/rohs-compliant package. * ep = exposed pad. package information for the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. package type package code outline no. land pattern no. 32 tqfn t3255+5 21-0140 90-0013 part temp range pin-package MAX2870etj+ -40 n c to +85 n c 32 tqfn-ep*
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated products, inc. 160 rio robles, san jose, ca 95134 usa 1-408-601-1000 24 ? 2012 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 4/12 initial release 1 7/12 updated int, frac, mod and r counter relationship section; updated formula in vco autoselect (vas) state machine section, updated table 8 13, 15, 20 MAX2870 23.5mhz to 6000mhz fractional/ integer-n synthesizer / vco

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