general description the MAX7377 dual-speed silicon oscillator with reset is a replacement for ceramic resonators, crystals, crystal oscillator modules, and discrete reset circuits. the device provides the primary and secondary clock source for microcontrollers in 3v, 3.3v, and 5v applica- tions. the MAX7377 features a factory-programmed high-speed oscillator, a 32.768khz oscillator, and a clock selector input. the clock output can be switched at any time between the high-speed clock and the 32.768khz clock for low-power operation. switchover is synchronized internally to provide glitch-free clock switching. unlike typical crystal and ceramic resonator oscillator circuits, the MAX7377 is resistant to vibration and emi. the high-output-drive current and absence of high- impedance nodes make the oscillator less susceptible to dirty or humid operating conditions. with a wide operating temperature range as standard, the MAX7377 is a good choice for demanding home appliance, industrial, and automotive environments. the MAX7377 is available in factory-programmed fre- quencies from 32.768khz to 10mhz. see table 1 for standard frequencies and contact the factory for cus- tom frequencies. the MAX7377 is available in a 5-pin sot23 package. refer to the max7383 data sheet for frequencies 10mhz. the MAX7377 standard operating tempera- ture range is -40 c to +125 c. see the applications information section for the extended operating temper- ature range. applications white goods handheld products automotive portable equipment consumer products microcontroller systems appliances and controls features ? 2.7v to 5.5v operation ? accurate high-speed 600khz to 10mhz oscillator ? accurate low-speed 32khz oscillator ? glitch-free switch between high speed and low speed at any time ? 10ma clock-output drive capability ? 2% initial accuracy ? 50ppm/? temperature coefficient ? 50% duty cycle ? 5ns output rise and fall time ? low jitter: 160ps (p-p) at 8mhz (no pll) ? 3ma fast-mode operating current (8mhz) ? 13? slow-mode operating current (32khz) ? -40? to +125? temperature range MAX7377 silicon oscillator with low-power frequency switching ________________________________________________________________ maxim integrated products 1 gnd v cc speed 15 e.c. clock MAX7377 sot23 top view 2 34 pin configuration ordering information 19-3474; rev 0; 10/04 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. the first two letters are ax. see table 1 at the end of the data sheet for the two-letter code. part temp range pin-package m ax 7377ax _ _- t -40 c to +125 c5 sot23-5 typical application circuit appears at end of data sheet.
MAX7377 silicon oscillator with low-power frequency switching 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = 2.7v to 5.5v, t a = -40? to +125 c, unless otherwise noted. typical values are at v cc = 5v and t a = +25 c.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v cc to gnd .............................................................-0.3v to +6v all other pins to gnd ................................-0.3v to (v cc + 0.3v) clock current ................................................................ 10ma continuous power dissipation (t a = +70 c) 5-pin sot23 (derate 7.1mw/ c above +70 c) ...................571mw (u5 - 2) operating temperature range .........................-40 c to +135 c junction temperature .....................................................+150 c storage temperature range.............................-60 c to +150 c lead temperature (soldering, 10s).................................+300 c parameter symbol conditions min typ max units operating supply voltage v cc 2.7 5.5 v f clock = 8mhz, no load 3 5 ma operating supply current i cc f clock = 32.768khz, no load 13 25 ? logic input (speed) input high voltage v ih 0.7 x v cc v input low voltage v il 0.3 x v cc v input current i in 2 a clock output v cc = 4.5v, i source = 9ma v cc - 0.4 output high voltage v oh v cc = 2.7v, i source = 2.5ma v cc - 0.4 v v cc = 4.5v, i sink = 20ma 0.4 output low voltage v ol v cc = 2.7v, i sink = 10ma 0.4 v v cc = 5v, t a = +25 c (note 2) -2 +2 initial fast clock frequency accuracy f fclock v cc = 2.7v to 5.5v, t a = +25? -4 +4 %
MAX7377 silicon oscillator with low-power frequency switching _______________________________________________________________________________________ 3 note 1: all parameters are tested at t a = +25?. specifications over temperature are guaranteed by design. note 2: the frequency is determined by part number selection. see table 1. note 3: guaranteed by design. not production tested. electrical characteristics (continued) (v cc = 2.7v to 5.5v, t a = -40? to +125 c, unless otherwise noted. typical values are at v cc = 5v and t a = +25 c.) (note 1) parameter symbol conditions min typ max units fast clock frequency temperature sensitivity (note 3) 50 325 ppm/ o c v cc = 5v, t a = +25 c (note 2) 32.440 32.768 33.096 initial slow clock frequency accuracy f sclock v cc = 2.7v to 5.5v, t a = +25? 31.785 33.751 khz slow clock frequency temperature sensitivity (note 3) 50 325 ppm/ o c clock output duty cycle 43 50 57 % clock output jitter observation of 8mhz output for 20s using a 500mhz oscilloscope 160 ps p-p clock output rise time t r 10% to 90% 5 ns clock output fall time t f 90% to 10% 5 ns startup delay v cc rising from 0 to 5v in 1? 100 ? t a = +25? 2.15 2.2 2.25 output undervoltage lockout uvlo v cc rising t a = -40? to +125? 2.05 2.35 v output undervoltage lockout hysteresis v thys 45 mv
MAX7377 silicon oscillator with low-power frequency switching 4 _______________________________________________________________________________________ duty cycle vs. temperature MAX7377 toc01 temperature ( c) duty cycle (%) 120 95 45 70 -5 20 -30 46 47 48 49 50 51 52 53 54 55 45 -55 clock = 32khz duty cycle vs. temperature MAX7377 toc02 temperature ( c) duty cycle (%) 120 95 45 70 -5 20 -30 46 47 48 49 50 51 52 53 54 55 45 -55 clock = 4mhz duty cycle vs. supply voltage MAX7377 toc03 supply voltage (v) duty cycle (%) 5.2 4.9 4.6 46 47 48 49 50 51 52 53 54 55 45 4.3 5.5 clock = 32khz duty cycle vs. supply voltage MAX7377 toc04 supply voltage (v) duty cycle (%) 5.2 4.9 4.6 46 47 48 49 50 51 52 53 54 55 45 4.3 5.5 clock = 4mhz supply current vs. temperature MAX7377 toc05 temperature ( c) supply current ( a) 120 95 45 70 -5 20 -30 10.5 11.0 11.5 12.0 12.5 13.0 13.5 14.0 10.0 -55 clock = 32khz supply current vs. temperature MAX7377 toc06 temperature ( c) supply current (ma) 120 95 45 70 -5 20 -30 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 0.5 -55 clock = 4mhz supply current vs. supply voltage MAX7377 toc07 supply voltage (v) supply current ( a) 5.2 4.9 4.6 0 5 10 15 20 25 30 4.3 5.5 clock = 32khz supply current vs. supply voltage MAX7377 toc08 supply voltage (v) supply current (ma) 5.2 4.9 4.6 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 0.5 4.3 5.5 clock = 4mhz frequency vs. supply voltage MAX7377 toc09 supply voltage (v) frequency (khz) 5.2 4.9 4.6 30.5 31.0 31.5 32.0 32.5 33.0 33.5 34.0 34.5 35.0 30.0 4.3 5.5 clock = 32khz t ypical operating characteristics (v cc = 5v, t a = +25 c, unless otherwise noted.)
MAX7377 silicon oscillator with low-power frequency switching _______________________________________________________________________________________ 5 frequency vs. supply voltage MAX7377 toc10 supply voltage (v) frequency (mhz) 5.2 4.9 4.6 3.92 3.94 3.96 3.98 4.00 4.02 4.04 4.06 4.08 4.10 3.90 4.3 5.5 clock = 4mhz frequency vs. temperature MAX7377 toc11 temperature ( c) frequency (khz) 120 95 45 70 -5 20 -30 32.1 32.2 32.3 32.4 32.5 32.6 32.7 32.8 32.9 33.0 32.0 -55 clock = 32khz frequency vs. temperature MAX7377 toc12 temperature ( c) frequency (mhz) 120 95 45 70 -5 20 -30 3.92 3.94 3.96 3.98 4.00 4.02 4.04 4.06 4.08 4.10 3.90 -55 clock = 4mhz 40ns/div clock MAX7377 toc13 clock output waveform (c l = 10pf) f = 4mhz, c l = 10pf 40ns/div clock MAX7377 toc14 clock output waveform (c l = 50pf) f = 4mhz, c l = 50pf 40ns/div clock MAX7377 toc15 clock output waveform (c l = 100pf) f = 4mhz, c l = 100pf 20 s/div MAX7377 toc16 high-speed to low-speed transition 400ns/div MAX7377 toc17 high-speed to low-speed transition (expanded scale) t ypical operating characteristics (continued) (v cc = 5v, t a = +25 c, unless otherwise noted.)
MAX7377 silicon oscillator with low-power frequency switching 6 _______________________________________________________________________________________ t ypical operating characteristics (continued) (v cc = 5v, t a = +25 c, unless otherwise noted.) detailed description the MAX7377 is a dual-speed clock generator for microcontrollers (?s) and uarts in 3v, 3.3v, and 5v applications. (figure 1). the MAX7377 is a replacement for two crystal oscillator modules, crystals, or ceramic resonators. the high-speed clock frequency is factory trimmed to specific values. a variety of popular stan- dard frequencies are available. the low-speed clock frequency is fixed at 32.768khz (table 1). no external components are required for setting or adjusting the frequency. supply voltage the MAX7377 has been designed for use in systems with nominal supply voltages of 3v, 3.3v, or 5v and is specified for operation with supply voltages in the 2.7v to 5.5v range. see the absolute maximum ratings sec- tion for limit values of power-supply and pin voltages. oscillator the clock output is a push-pull configuration and is capable of driving a ground-connected 500 ? or a posi- tive-supply-connected 250 ? load to within 400mv of either supply rail. the clock output remains stable over the full operating voltage range and does not generate short output cycles when switching between high- and low-speed modes. a typical startup characteristic is shown in the typical operating characteristics . clock-speed select input the MAX7377 uses a logic input pin, speed, to set clock speed. take this pin low to select slow clock speed (nominally 32.768khz) or high to select full clock speed. the speed input can be strapped to v cc or to gnd to select fast or slow clock speed, or connected to a logic output (such as a processor port) used to change clock speed on the fly. if the speed input is connected to a processor port that powers up in the pin description pin name function 1 clock push-pull clock output 2 gnd ground 3 speed clock-speed select input. drive speed low to select the 32khz fixed frequency. drive speed high to select factory-trimmed frequency. 4v cc positive supply voltage. bypass v cc to gnd with a 0.1? capacitor. 5 e.c. must be externally connected to v cc 20 s/div MAX7377 toc18 low-speed to high-speed transition clock speed 400ns/div MAX7377 toc19 low-speed to high-speed transistion (expanded scale)
MAX7377 silicon oscillator with low-power frequency switching _______________________________________________________________________________________ 7 input condition, connect a pullup or pulldown resistor to the speed input to set the clock to the preferred speed on power-up. the leakage current through the resistor into the speed input is very low, so a resistor value as high as 500k ? may be used. applications information interfacing to a microcontroller clock input the MAX7377 clock output is a push-pull, cmos, logic output that directly drives any microprocessor ( p) or ? clock input. there are no impedance-matching issues when using the MAX7377. the MAX7377 is not sensitive to its position on the board and does not need to be placed right next to the ?. refer to the microcon- troller data sheet for clock-input compatibility with exter- nal clock signals. the MAX7377 requires no biasing components or load capacitance. when using the MAX7377 to retrofit a crystal oscillator, remove all bias- ing components from the oscillator input. output jitter the MAX7377? jitter performance is given in the electrical characteristics table as a peak-to-peak value obtained by observing the output of the MAX7377 for 20s with a 500mhz oscilloscope. jitter values are approximately proportional to the period of the output frequency of the device. thus, a 4mhz part has approximately twice the jitter value of an 8mhz part. the jitter performance of clock sources degrades in the presence of mechanical and electrical interference. the MAX7377 is relatively immune to vibration, shock, and emi influences, and thus provides a considerably more robust clock source than crystal or ceramic res- onator-based oscillator circuits. initial power-up and operation an internal power-up reset disables the oscillator until v cc has risen above 2.2v. the clock then starts up within 30? (typ) at the frequency determined by the speed pin. extended temperature operation the MAX7377 was tested to +135? during product characterization and shown to function normally at this temperature (see the typical operating characteristics ). however, production test and qualifi- cation is only performed from -40? to +125? at this time. contact the factory if operation outside this range is required. power-supply considerations the MAX7377 operates with a 2.7v and 5.5v power- supply voltage. good power-supply decoupling is needed to maintain the power-supply rejection perfor- mance of the MAX7377. bypass v cc to gnd with a 0.1? surface-mount ceramic capacitor. mount the bypass capacitor as close to the device as possible. if possible, mount the MAX7377 close to the microcon- troller? decoupling capacitor so that additional decou- pling is not required. a larger value bypass capacitor is recommended if the MAX7377 is to operate with a large capacitive load. use a bypass capacitor value of at least 1000 times that of the output load capacitance. logic 32khz (lf oscillator) por mux clock speed v cc MAX7377 600khz to 10mhz (hf oscillator) figure 1. functional diagram
MAX7377 silicon oscillator with low-power frequency switching 8 _______________________________________________________________________________________ MAX7377 clock osc1 osc2 c i/o port v cc supply voltage e.c. speed t ypical application circuit suffix standard frequency (mhz) mg 1 ok 1.8432 qt 3.39545 qw 3.6864 rd 4 rh 4.1943 tp 8 table 1. standard frequencies part pin-package frequency (hz) top mark MAX7377axmg 5 sot23 1m aene MAX7377axok 5 sot23 1.8432m aend MAX7377axqt 5 sot23 3.39545m aemy MAX7377axqw 5 sot23 3.6864m aemz MAX7377axrd 5 sot23 4m aena MAX7377axrh 5 sot23 4.1943m aenb MAX7377axtp 5 sot23 8m aenc table 2. standard part numbers for all other reset threshold options, contact factory. chip information transistor count: 2027 process: bicmos
MAX7377 silicon oscillator with low-power frequency switching maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 _____________________ 9 2004 maxim integrated products printed usa is a registered trademark of maxim integrated products. package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) sot-23 5l .eps e 1 1 21-0057 package outline, sot-23, 5l
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