View MAX1727EUG_1272544.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-1489; Rev 0; 12/00
GSM Cellular/PCN Handset RF Power Management IC MAX1727
General Description
The MAX1727 is a radio frequency (RF) power-management IC intended for Global Satellite Mobile (GSM) communication cellular and personal cellular network (PCN) handsets using a single lithium-ion (Li+) cell battery with inputs from +3.1V to +5.5V. The IC contains four low-noise, low-dropout (LDO) linear regulators to provide all the supply voltage requirements for the RF portion of the handset, and two high-speed, wide-bandwidth op amps for the power amplifier (PA) power control loop. Each LDO has its own individual on/off control to maximize design flexibility. All LDOs are internally trimmed to a fixed output voltage and are optimized for low noise and high crosstalk isolation. LDO1 (R1OUT) is rated for 100A and is optimized for lowest quiescent current. It is intended to power the transmitter, receiver, and synthesizer. LDO2 (R2OUT) is rated for 50mA. It is intended to power the TCXO, GSM, and PCN highpower voltage-controlled oscillators (VCOs). LDO3 (R3OUT) is rated for 20mA and is optimized to suppress line transients. It is intended to power the UHF offset VCO. LDO3 has an auxiliary 2.5 switched output to allow the VCO to be powered up with precise timing. LDO4 (R3BYP) is rated for 20mA. It is intended to power this IC's reference and LDO3 for superior line rejection. LDO4 and the reference will be powered on if any of the R1EN, R2EN, and R3EN enable inputs are logic high. The op amps have wide bandwidth, high DC accuracy, high slew rate, and Rail-to-Rail(R) inputs and outputs. The op amps can sink and source 3mA, and include two 2.5 switched outputs. The op amps and switched outputs may be used independently or may be configured to provide optimized power for a PA control loop. o +3.1V to +5.5V Input Range o One 2.90V, 100mA Low IQ LDO o One 2.75V, 50mA Low IQ LDO o One 2.75V, 20mA Low IQ LDO o Low-Noise LDOs <90VRMS from 10Hz to 100kHz >80dB Crosstalk Isolation at 10kHz >70dB PSRR at 1kHz o 5% Accuracy Over Line, Load, and Temperature o Three 2.5 Switched Outputs o Current and Thermal Limit o Two Undedicated Op Amps Rail-to-Rail CMR Inputs and Outputs >120dB Channel Separation >85dB PSRR at 1kHz o 10A (max) Shutdown Current
Features
Ordering Information
PART MAX1727EUG TEMP. RANGE -40C to +85C PIN-PACKAGE 24 TSSOP
Pin Configuration
R3EN 1 PCEN 2 24 GND 23 CBYP 22 ENVCO 21 VCOOUT 20 R3OUT MAX1727 19 R3BYP 18 R1OUT 17 VCC 16 R2OUT 15 R2EN 14 R1EN 13 GSM/PCN TSSOP
Applications
GSM Cellular or PCN Handsets Single-Cell Li+ Systems 3-Cell NiMH, NiCD, or Alkaline Systems
PC1+ 3 PC1- 4 PC1OUT 5 VPC 6 PC2OUT 7 PC2- 8 PC2+ 9 PCNAPC 10
Typical Application Circuit and Functional Diagram appear at end of data sheet. Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
BANDSWIN 11 GSMAPC 12
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
GSM Cellular/PCN Handset RF Power Management IC MAX1727
ABSOLUTE MAXIMUM RATINGS
VCC, VPC to GND......................................................-0.3V to +7V PC1-, PC1+, PC2-, PC2+ to GND ............................-0.3V to +7V GSM/PCN, BANDSWIN to GND ...............................-0.3V to +7V PC1OUT, PC2OUT to GND ......................................-0.3V to +7V R1OUT, R2OUT, R3BYP to GND................-0.3V to (VCC + 0.3V) R3OUT, CBYP to GND ..........................-0.3V to (VR3BYP + 0.3V) R1EN, R2EN, R3EN, ENVCO, PCEN to GND ..........................................-0.3V to (VCC + 0.3V) VCOOUT to GND ..................................-0.3V to (VR3OUT + 0.3V) GSMAPC, PCNAPC to GND ...........-0.3V to (VBANDSWIN + 0.3V) Continuous Power Dissipation (TA = +70C) 24-Pin TSSOP (derate 12.2mW/C above +70C) ......975mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature(soldering, 10s) ..................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation 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.
ELECTRICAL CHARACTERISTICS
(VCC = +3.1V to +5.5V, VPC = +2.8V to +5.5V, GND = 0, CBYP = 0.01F, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER VCC Operating Voltage VPC Operating Voltage UVLO Falling UVLO Rising SUPPLY CURRENT Supply Current in Shutdown VCC + VPC Supply Current REFERENCE Reference Bypass Output REF Supply Rejection REGULATOR R1 R1OUT Output Voltage Dropout Voltage Load Regulation Line Regulation R1OUT Leakage Current REGULATOR R2 R2OUT Output Voltage Dropout Voltage Load Regulation Line Regulation R2OUT Leakage Current REGULATOR R3 R3OUT Output Voltage Dropout Voltage 0.1mA IR3OUT 20mA IR3OUT = 1mA IR3OUT = 20mA 2.61 2.75 1 45 100 2.90 V mV 0.1mA IR2OUT 50mA IR2OUT = 1mA IR2OUT = 50mA 0.1mA IR2OUT 50mA +3.1V VCC +5.5V, IR2OUT = 10mA R2EN, R2OUT = 0, VCC = +5.5V 2.61 2.75 1 100 8 0.5 225 45 10 2 mV mV A 2.90 V mV 0.1mA IR1OUT 100mA IR1OUT = 1mA IR1OUT = 100mA 0.1mA IR1OUT 100mA +3.1V VCC +5.5V, IR1OUT = 10mA R1EN, R1OUT = 0, VCC = +5.5V 2.80 2.90 1 100 8 0.5 225 45 10 2 3.00 V mV mV mV A ICBYP = 0, do not draw current from this pin +3.1V VCC +5.5V 1.225 1.250 0.2 1.275 5 V mV All regulators and op amps off, VCC = +3.6V All regulators and op amps on, VCC = VPC 0.01 1.80 10 3.0 A mA VCC falling VCC rising CONDITIONS MIN 3.1 2.8 2.3 2.4 2.5 2.62 TYP MAX 5.5 5.5 UNITS V V V V
2
_______________________________________________________________________________________
GSM Cellular/PCN Handset RF Power Management IC
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.1V to +5.5V, VPC = +2.8V to +5.5V, GND = 0, CBYP = 0.01F, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.)
PARAMETER Load Regulation Line Regulation R3OUT Leakage Current VCOOUT SWITCH (R3 SWITCH) On-Resistance REGULATOR R4 (R3BYP) R3BYP Output Voltage Dropout Voltage Load Regulation Line Regulation R3BYP Leakage Current Input Offset Voltage Input Bias Current Input Bias Current Shutdown Mode Input Offset Current Input Common-Mode Range Gain-Bandwidth Product Slew Rate PSRR CMRR Output Voltage Swing On-Resistance GSMAPC On-Resistance PCNAPC Input Low Level Input High Level Logic Input Current Threshold Rising Hysteresis IOUT = 1mA 0 < VIN < +5.5V 150 20 THERMAL SHUTDOWN (R3 SWITCH) C C 2.0 1 10Hz f 1kHz 10Hz f 1kHz ILOAD = 3 mA 0.3V < VGSMAPC < VPC - 0.3V, ILOAD = 3 mA 0.3V < VPCNAPC < VPC - 0.3V, ILOAD = 3 mA 0.2 2.2 2.2 RLOAD = 1k connected to VPC/2, CLOAD = 100pF to GND 0.3 4 1 85 80 2.62 5 5 0.4 VCM = +0.3V to (VPC - 0.3V) VCM = 0 to VCC, VPC = 0, PCEN = GND 2.4 0.1mA IR3BYP 20mA IR3BYP = 1mA IR3BYP = 20mA 0.1mA IR3BYP 20mA +3.1V VCC +5.5V, IR3BYP = 10mA R1EN, R2EN, R3EN = 0, R3BYP = 0, VCC = +5.5V 2.85 2.95 1 45 10 0.7 100 45 10 2 2 150 5 30 VPC 0.3 5.1 3.05 V mV mV mV A mV nA A nA V MHz V/s dB dB V V V A CONDITIONS 0.1mA IR3OUT 20mA +3.1V VCC +5.5V, IR3OUT = 10mA R3EN, R3OUT = 0, VCC = +5.5V MIN TYP 5 0.2 MAX 45 10 2 UNITS mV mV A
MAX1727
PA CONTROL OP AMPS (PC1, PC2)
BAND SWITCH (GSMAPC, PCNAPC)
LOGIC AND CONTROL INPUTS (R1EN, R2EN, R3EN, ENVCO, GSM/PCN, PCEN)
_______________________________________________________________________________________
3
GSM Cellular/PCN Handset RF Power Management IC MAX1727
ELECTRICAL CHARACTERISTICS
(VCC = +3.1V to +5.5V, VPC = +2.8V to +5.5V, GND = 0, CBYP = 0.01F, TA = -40C to +85C, unless otherwise noted.) (Note 1)
PARAMETER VCC Operating Voltage VPC Operating Voltage UVLO Falling UVLO Rising SUPPLY CURRENT Supply Current in Shutdown VCC Supply Current REFERENCE Reference Bypass Output REF Supply Rejection REGULATOR R1 R1OUT Output Voltage Dropout Voltage Load Regulation Line Regulation R1OUT Leakage Current REGULATOR R2 R2OUT Output Voltage Dropout Voltage Load Regulation Line Regulation R2OUT Leakage Current REGULATOR R3 R3OUT Output Voltage Dropout Voltage Load Regulation Line Regulation R3OUT Leakage Current VCOOUT SWITCH (R3 SWITCH) On-Resistance REGULATOR R4 (R3BYP) R3BYP Output Voltage Dropout Voltage Load Regulation Line Regulation R3BYP Leakage Current 0.1mA IR3BYP 20mA IR3BYP = 20mA 0.1mA IR3BYP 20mA +3.1V VCC +5.5V, IR3BYP = 10mA R1EN, R2EN, R3EN = 0, R3BYP = 0, VCC = +5.5V 2.85 3.05 100 45 10 2 V mV mV mV A 5.1 0.1mA IR3OUT 20mA IR3OUT = 20mA 0.1mA IR3OUT 20mA +3.1V VCC +5.5V, IR3OUT = 10mA R3EN, R3OUT = 0, VCC = +5.5V 2.61 2.90 100 45 10 2 V mV mV mV A 0.1mA IR2OUT 50mA IR2OUT = 50mA 0.1mA IR2OUT 50mA +3.1V VCC +5.5V, IR2OUT = 10mA R2EN, R2OUT = 0, VCC = +5.5V 2.61 2.90 225 45 10 2 V mV mV mV A 0.1mA IR1OUT 100mA IR1OUT = 100mA 0.1mA IR1OUT 100mA +3.1V VCC +5.5V, IR1OUT = 10mA R1EN, R1OUT = 0, VCC = +5.5V 2.80 3.00 225 45 10 2 V mV mV mV A ICBYP = 0, do not draw current from this pin +3.1V VCC +5.5V 1.219 1.281 5 V mV All regulators and op amps off, VCC = +3.6V All regulators and op amps on 10 3.0 A mA VCC falling VCC rising CONDITIONS MIN 3.1 2.8 2.3 2.62 MAX 5.5 5.5 UNITS V V V V
4
_______________________________________________________________________________________
GSM Cellular/PCN Handset RF Power Management IC MAX1727
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.1V to +5.5V, VPC = +2.8V to +5.5V, GND = 0, CBYP = 0.01F, TA = -40C to +85C, unless otherwise noted.) (Note 1)
PARAMETER PA CONTROL OP AMPS (PC1, PC2) Input Offset Voltage Input Bias Current Input Bias Current Shutdown Mode Input Offset Current Input Common-Mode Range Output Voltage Swing On-Resistance GSMAPC On-Resistance PCNAPC Input Low Level Input High Level Logic Input Current 0 < VIN < +5.5V 2.0 1 ILOAD = 3 mA 0.3V < VGSMAPC < VPC- 0.3V, ILOAD = 3 mA 0.3V < VPCNAPC < VPC- 0.3V, ILOAD = 3 mA 0.3 0.2 VCM = 0.3V to (VPC - 0.3V) VCM = 0 to VCC, VPC = 0, PCEN = GND 2 150 5 30 VPC - 0.3 2.62 5 5 0.4 nA A nA V V V V A CONDITIONS MIN TYP MAX UNITS
BAND SWITCH (GSMAPC, PCNAPC)
LOGIC AND CONTROL INPUTS (R1EN, R2EN, R3EN, ENVCO, GSM/PCN, PCEN)
Note 1: Specifications to -40C are guaranteed by design, not production tested.
Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
GROUND CURRENT vs. SUPPLY VOLTAGE
FULL LOAD* 1.2 GROUND CURRENT (mA) 1.0 0.8 0.6 0.4 0.2 0 0 1 2 *ALL REGULATORS ON 3 4 5 NO LOAD*
MAX1727 toc01
GROUND CURRENT vs. LOAD CURRENT
MAX1727 toc02
OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
MAX1727 toc03
1.4
1.135 1.130 GROUND CURRENT (mA) 1.125 1.120 1.115 1.110 1.105 1.100 0 20 40 60 LOAD CURRENT (mA) VCC = +3.6V 80 LDO3 LDO1
2.95 2.90 OUTPUT VOLTAGE (V) LDO1 2.85 2.80 2.75 2.70 2.65 2.7 3.2 3.7 4.2 4.7 5.2 SUPPLY VOLTAGE (V) LDO2
LDO3
LDO2
100
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
GSM Cellular/PCN Handset RF Power Management IC MAX1727
Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX1727 toc04
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX1727 toc05
REGULATOR PSRR vs. FREQUENCY (RLOAD = 300)
90 80 70 PSRR (dB) 60 50 40 30 20 LDO1 LDO2 LDO3
MAX1727 toc06
2.92 2.90 2.88 OUTPUT VOLTAGE (V) 2.86 2.84 2.82 2.80 2.78 2.76 2.74 2.72 0 20 40 60 80 LDO3 LDO2 VCC = +3.6V LDO1
100 90 80 DROPOUT VOLTAGE (mV) 70 60 50 40 30 20 10 0 0 20 40 60 80 VCC = +3.6V LDO1 LDO3 LDO2
100
10 0 1 10 100 1k 10k 100k 1M
100
100
LOAD CURRENT (mA)
LOAD CURRENT (mA)
FREQUENCY (Hz)
REGULATOR ISOLATION vs. FREQUENCY (RL = 300)
MAX1727 toc07
GAIN AND PHASE vs. FREQUENCY (RL = 1k, CL = 100pF)
80 60 40 20 0 -20 -40 -60 -80 -100 -120 -140 -160 -180 10 100 1k
MAX1727 toc08
INPUT OFFSET VOLTAGE vs. TEMPERATURE
400 300 OFFSET VOLTAGE (V) 200 100 0 -100 -200 -300 -400 -500
MAX1727 toc09
120 LDO1 TO LDO2 REGULATOR ISOLATION (dB) 100 80 LDO1 TO LDO3 60 40 20 0 10 100 1k 10k 100k
500
GAIN
GAIN (dB)/PHASE (DEGREES)
PHASE
1M
FREQUENCY (Hz)
10k 100k FREQUENCY (Hz)
1M
10M
-40
-15
10
35
60
85
TEMPERATURE (C)
INPUT OFFSET VOLTAGE DISTRIBUTION
MAX1727 toc10
BAND SWITCH ON-RESISTANCE vs. BANDSWIN VOLTAGE
4.5 4.0 ON-RESISTANCE () 3.5 3.0 2.5 VCC = +2.8V
MAX1727 toc11
LINE-TRANSIENT RESPONSE REGULATOR 1
MAX1727 toc12
60 50 NUMBER OF UNITS 40 30 20 10 0
193 UNITS VCM = 0.3V TA = +25C
5.0
4.0V VIN 3.6V
1.5 1.0 0.5 VCC = +5.5V
VOUT
ILOAD = 10mA 0 1 2 3 4 5 6 40s/div
-600
-350
-100
100
OFFSET VOLTAGE (V)
300
800
-10
50
0 BANDSWIN VOLTAGE (V)
6
_______________________________________________________________________________________
20mV/div AC-COUPLED
2.0
GSM Cellular/PCN Handset RF Power Management IC
Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE REGULATOR 1
MAX1727 toc13
MAX1727
LINE-TRANSIENT RESPONSE REGULATOR 2
MAX1727 toc14
LOAD-TRANSIENT RESPONSE REGULATOR 2
MAX1727 toc15
IOUT
100mA 10mA
VIN
4.0V 3.6V IOUT 50mA 5mA
50mV/div AC-COUPLED
20mV/div AC-COUPLED
VOUT
VOUT
VOUT
ILOAD = 10mA 40s/div 40s/div 40s/div
ILOAD = 10mA
LINE-TRANSIENT RESPONSE REGULATOR 3
MAX1727 toc16
LOAD-TRANSIENT RESPONSE REGULATOR 3
MAX1727 toc17
4.0V VIN 3.6V IOUT 0.1mA 10mA
20mV/div AC-COUPLED
VOUT ILOAD = 10mA 40s/div
VOUT
40s/div
OP AMP LARGE-SIGNAL TRANSIENT RESPONSE
MAX1727 toc18
OP AMP SMALL-SIGNAL TRANSIENT RESPONSE
MAX1727 toc19
5V OUT 0 IN
5V IN AV = +1V/V RL = 1k 20s/div 0 OUT AV = +1V/V RL = 1k 1s/div
0
_______________________________________________________________________________________
50mV/div AC-COUPLED
200mV
0
200mV
50mV/div AC-COUPLED
7
GSM Cellular/PCN Handset RF Power Management IC MAX1727
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 NAME R3EN PCEN PC1+ PC1PC1OUT VPC PC2OUT PC2PC2+ PCNAPC BANDSWIN GSMAPC GSM/PCN R1EN R2EN R2OUT VCC R1OUT R3BYP R3OUT VCOOUT ENVCO CBYP GND Regulator R3 Enable Input Op Amp and Band Switch Mux Enable Input Op Amp 1 Noninverting Input Op Amp 1 Inverting Input Op Amp 1 Output Op Amp Power Supply Op Amp 2 Output Op Amp 2 Inverting Input Op Amp 2 Noninverting Input Band Switch PCN Output. Normally connected to PCN PA APC. Internally shorts to ground when not selected. Band Switch Input. Normally connected to PC2OUT. Band Switch GSM Output. Normally connected to GSM PA APC. Internally shorts to ground when not selected. Band Switch Control Input. With logic high, BANDSWIN is connected to GSMAPC. With logic low, BANDSWIN is connected to PCNAPC. Regulator R1 Enable Input Regulator R2 Enable Input Output of Linear Regulator 2. 50mA output current. Use 1F low ESR bypass capacitor to GND. Regulator Power Supply Output of Linear Regulator 1. 100mA output current. Use 1F low ESR bypass capacitor to GND. Output of Linear Regulator 4. Power supply for regulator R3 and 1.25V reference. Use 1F low ESR bypass capacitor to GND. Output of Linear Regulator 3. 20mA output current. Use 1F low ESR bypass capacitor to GND. Switched R3 Output VCO Switch Control Input. With logic high, VCOOUT is connected to R3OUT. With logic low, VCOOUT is high impedance. 1.25V Voltage Reference Bypass Pin. Connect low-leakage, 0.01F bypass capacitor to GND to minimize noise at the output. Ground FUNCTION
8
_______________________________________________________________________________________
GSM Cellular/PCN Handset RF Power Management IC
Detailed Description
The MAX1727 is an ideal RF power management IC for the GSM cellular phone. The MAX1727 contains four LDOs, three switches, and two high-speed, high-bandwidth op amps. The LDOs power transmitter, receiver, synthesizer, TCXO, and VCOs. The switches are used to optimize power consumption and to sequence power properly. The op amps provide essential loop control for the PA. The MAX1727 contains all the building blocks necessary to design a high-performance RF circuit (see Typical Application Circuit). The MAX1727 has an input voltage range of +3.1V to +5.5V, perfect for single-cell Li+ cell or 3-cell NiMH battery applications. If any one of LDO1 through LDO3 is enabled, LDO4 and the internal 1.25V reference are powered on. Once LDO4 and the reference voltage reach regulation, the commanded LDOs are powered on. All three LDOs (LDO1, LDO2, LDO3) must be disabled to shut down the internal reference. LDO4 is used as a preregulator to provide extremely high PSRR of 90dB at 1kHz for LDO3. The output current capability of LDO3 and LDO4 is limited to 20mA. LDO4 output can be loaded as long as total current demand by LDO4 load and LDO3 load is less than 20mA. Clear transmission and reception can only be achieved with a low-noise power supply. All the LDOs of the MAX1727 are designed with <90V RMS noise from 10Hz to 100kHz, and each LDO achieves >70dB PSRR. The band switches of the MAX1727 are both grounded when PCEN is in logic low state. When PCEN is in logic high state, GSM/PCN determines the switch positions. If GSM/PCN is low, PCNAPC is engaged. If GSM/PCN is high, GSMAPC output is engaged. All the regulators feature high PSRR and excellent load and line regulation characteristics and are designed for single Li+ battery applications where a pulsed current demand is required from the battery. For a load requiring significant isolation from transients on the input, REG3 should be used with REG4 configured as a preregulator to provide improved rejection. The minimum I/O voltage differential (dropout voltage) determines the lowest usable supply voltage. Once dropout has been reached, the series pass transistor is fully on, and regulation ceases. The output will track the input voltage as the input voltage is further lowered. For a P-channel series pass element (as used here), dropout voltage is a function of drain-to-source on-resistance multiplied by the load current. Each regulator features a P-channel MOSFET series pass transistor sized to deliver the rated output current for each regulator. A P-channel MOSFET requires almost no drive current to the gate. This significantly reduces the quiescent current compared to bipolar PNP series pass transistor regulators, particularly in dropout when the DC current gain of the PNP transistor is reduced to nearly unity. A MOSFET design retains its low quiescent current even in dropout, with and without load.
MAX1727
Reference Bypass
An external bypass capacitor is connected to CBYP to reduce the inherent reference noise. The capacitor forms a lowpass filter in conjunction with an internal network. Use a 0.01F nonpolarized capacitor connected as close to the CBYP pin as possible. For lowest noise, increase the bypass capacitor to 0.1F. Values above 100nF provide no performance improvement and are therefore not recommended. Do not place any additional loading on this pin. Regulator Short-Circuit Protection Each regulator has a separate current-limit circuit within the overall feedback loop. The typical values for current limit are: REG1 = 250mA; REG2/REG3/REG4 = 125mA. Each regulator will survive a continuous short circuit at the output, until the IC thermal limit control powers down all the regulators. Thermal Overload Protection Thermal overload protection limits the total power dissipation by measuring the die temperature. When +150C is reached, the thermal sensor signals the shutdown logic for all the regulators. Once the die temperature cools by 20C, the regulators will restart. If the overload persists, the regulators will cycle on and off as the die temperature fluctuates.
9
Linear Regulators
Regulators 1-4 are low-noise, low-dropout, low-quiescent-current linear regulators. Each regulator consists of an error amplifier, internal feedback voltage-divider, and P-channel MOSFET pass transistor. All regulators share a 1.25V reference. The reference is connected to the inverting input of each of the regulator's error amplifiers. The error amplifiers compare the reference with the feedback voltage from each of the regulator outputs and amplify the difference. If the feedback voltage is lower than the reference voltage, the pass transistor gate is pulled lower, which allows more current to pass into the output load to increase the output voltage. If the feedback voltage is too high, the pass transistor gate is pulled up, allowing less current into the load. The feedback is provided by an internal, trimmed resistor-divider connected at each of the regulator outputs.
_______________________________________________________________________________________
GSM Cellular/PCN Handset RF Power Management IC
Capacitor Selection and Regulator Stability Minimum recommended output capacitance for all the regulators is 1F with a maximum ESR of 0.4. For lower noise requirements, use a 10F capacitor on each regulator. Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. Z5U and Y5V dielectrics may require a minimum value of 2.2F nominal output capacitance, especially a low temperature operation. power supply. The logic-controlled changeover is gated by the op amp enable line (PCEN). Figure 1 shows a single op amp within the MAX1727 used in a dual PA APC loop. The RF envelope at the active PA output is sampled by the 20dB coupler and detected by the temperature-compensated dual Schottky diode pair. The baseband DAC ramp control is summed with the averaged detected envelope by an inverting integrator stage to produce an APC signal. This is connected to the operational PA by the SPDT switch. The unused PA APC line is grounded. This prevents the unused PA from accidentally powering up. Also, a grounded APC line keeps the PA in a low-quiescent-current standby mode. Figure 2 shows an alternative method of PA control where the average DC supply current to the active PA is used as a measure of the average RF power into the load (antenna). The circuit takes advantage of the railto-rail performance and CMRR of the op amps. The PA average DC current is sampled by the sense resistor and amplified differentially before summation into the second integrating stage with the baseband ramp DAC signal. As shown in Figure 1, the APC signal is routed through the SPDT switches to the active PA.
MAX1727
Op Amps
Two uncommitted unity-gain-stable op amps are available for use in the MAX1727. Gain bandwidth is typically 4MHz and slew rate 1V/s. Gain and phase margins are typically 8dB and 63 when loaded with 1k and 100pF at the output. The input stages are differential CMOS transistors providing an input common-mode range extending to 300mV within the positive supply rail (VPC) and ground. Input offset voltage is 2mV (max), with bias current of 150nA (max). A separate supply input is provided for the two op amps, allowing them to be powered by supplies different from REG1-REG4. The amplifier's excellent PSRR to beyond 1kHz allows the supply to be connected directly to the battery. Decouple the supply pin (VPC) with a 0.1F ceramic capacitor in parallel with at least 1F. Place the 0.1F as close to the supply pin as possible. Both op amps have a common logic-controlled shutdown pin, allowing the inputs to remain connected to a supply while reducing quiescent current to a very low level. The op amp supply current is reduced to 5A during shutdown mode. The output stages are all CMOS, allowing rail-to-rail swing at the output (load dependent). For a 3mA load, the output will swing to within 200mV of either the positive supply (VPC) or ground. If an op amp is unused, the positive input should be connected to ground, and the output should be connected back to the negative input. Connecting an unused op amp as a grounded unitygain buffer prevents oscillation and saturation, which causes inconsistent supply-current consumption.
Chip Information
TRANSISTOR COUNT: 1324
Power Switches
The MAX1727 contains three 2.5 CMOS switches. One is connected to the REG3 output and is suitable for fast enabling of a load. The other two switches are wired as SPDT switches and are used to route the APC outputs from a loop amplifier. When not required, the APC control is grounded. This prevents spurious power-up of the unused PA and eliminates a low onresistance, high-current switch in series with the PA
10
______________________________________________________________________________________
GSM Cellular/PCN Handset RF Power Management IC MAX1727
VRF
VPC
PC1+ OP1 PC1PC2OUT PCEN PC1OUT
PC2OP2 PC2+ PA CONTROL RAMP FROM BB CONTROL DAC
MAX1727 GSM PA BANDSWIN GSMAPC 20dB COUPLER GSM/PCN PCN PA
PCNAPC
GND
Figure 1. Single Op Amp PA Automatic Power Control Loop
______________________________________________________________________________________
11
GSM Cellular/PCN Handset RF Power Management IC MAX1727
FROM BATTERY
VPC PC1+ RSENSE OP1 PC1PC2OUT DC SUPPLY TO PA PC1OUT
PC2OP2 PC2+ PA CONTROL RAMP FROM BB CONTROL DAC
PCEN
MAX1727 BANDSWIN GSMAPC
GSM PA
20dB COUPLER GSM/PCN PCN PA
PCNAPC
GND
Figure 2. High-Side Average Current-Sense PA Control
12
______________________________________________________________________________________
GSM Cellular/PCN Handset RF Power Management IC MAX1727
Typical Application Circuit
+3.1V TO +5.5V Li+ BATTERY R1EN REG2 R2OUT 1F R2EN REG3 R3OUT 1F R3EN ENVCO 2.75V 20mA
VCC
R1OUT REG1 1F
2.90V 100mA
2.75V 50mA
VCOOUT R3BYP CBYP 0.01F +2.8V TO +5.5V 2.95V 20mA 1F
REG4
REF
VPC MAX1727 PC1+ OP1 PC1PC2OUT OP2 PC2PCEN PC1OUT PC2+
BANDSWIN GSMAPC
PCNAPC GSM/PCN
GND
______________________________________________________________________________________
13
GSM Cellular/PCN Handset RF Power Management IC MAX1727
Functional Diagram
+3.1V TO +5.5V 2.90V 100mA 2.75V 50mA 2.75V 20mA 2.95V 20mA
R1OUT VCC R1EN R2EN R3EN PC1+ OP1 PC1PC2OUT OP2 PC2BANDSWIN GSMAPC PC1OUT PC2+ MAX1727 LOW-DROPOUT LINEAR REGULATORS R2OUT R3OUT R3BYP
PCNAPC GND
14
______________________________________________________________________________________
GSM Cellular/PCN Handset RF Power Management IC
Package Information
TSSOP,NO PADS.EPS
MAX1727
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.
15 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX1727EUG

	To Download MAX1727EUG Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .