MAX4473EUA ,Low-Cost / Low-Voltage / PA Power Control Amplifier for GSM Applications in 8-Pin MAXFeaturesThe MAX4473 PA power control IC is intended for' Optimized for GSM Timing Requirementsclose ..
MAX4473EUA+ ,Low-Cost, Low-Voltage, PA Power Control Amplifier for GSM ApplicationsELECTRICAL CHARACTERISTICS(V = 2.7V to 6.5V, SHDN > 2.4V, MAX4473 test circuit, RG1 = RG2 = 1kΩ ±1% ..
MAX4473EUA+T ,Low-Cost, Low-Voltage, PA Power Control Amplifier for GSM ApplicationsFeaturesThe MAX4473 PA power control IC is intended for♦ Optimized for GSM Timing Requirementsclose ..
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MAX8510EXK28-T ,2.8 V, Ultra-low-noise, high PSRR, low-dropout, 120 mA linear regulator
MAX8510EXK29 ,Ultra-Low-Noise, High PSRR, Low-Dropout, 120mA Linear RegulatorsMAX8510/MAX8511/MAX851219-2732; Rev 0; 1/03Ultra-Low-Noise, High PSRR, Low-Dropout,120mA Linear Reg ..
MAX8510EXK29+T ,Ultra-Low-Noise, High PSRR, Low-Dropout, 120mA Linear RegulatorsApplicationsMAX8510EXKxy-T -40°C to +85°C 5 SC70-5Cellular and Cordless PhonesMAX8511EXKxy-T -40°C ..
MAX4473ESA-MAX4473EUA
Low-Cost / Low-Voltage / PA Power Control Amplifier for GSM Applications in 8-Pin MAX
General DescriptionThe MAX4473 PA power control IC is intended for
closed-loop bias control of GSM power amplifiers. The
device facilitates accurate control of the current deliv-
ered to the power amplifier (PA) via a control voltage.
The error amplifier senses the voltage drop across an
external current-sense resistor placed between the
supply and the PA. The output of the error amplifier
adjusts the PA gain until the current is proportional to
the power control voltage applied to the MAX4473. This
unique topology is useful in time-division-multiple-
access (TDMA) systems, such as GSM, where accurate
transmit burst shaping and power control is required.
User-selectable current sensing and gain setting resis-
tors maximize flexibility.
The MAX4473 operates from a single +2.7V to +6.5V
supply and typically draws 1.2mA of supply current.
The error amplifier has a common-mode range that
extends from +1V to VCC. The power control input and
error amplifier outputs swing Rail-to-Rail®. A low-power
shutdown mode reduces supply current to less than
1µA and activates an on-board active pull-down at the
error amplifier output. Fast enable/disable times of
0.9µs reduce average power consumption without com-
promising dynamic performance. The MAX4473 is
available in a space-saving 8-pin µMAX package.
ApplicationsGSM Cellular Phones
Cordless Phones
Precision Current Control
High-Frequency Servo Loops
FeaturesOptimized for GSM Timing Requirements+2.7V to +6.5V Single-Supply Operation1.2mA Supply Current≤1µA Supply Current in Shutdown Mode
Guaranteed 1.5µs Enable/Disable TimesActive Output Pull-Down in Shutdown ModeRail-to-Rail Error Amplifier OutputRail-to-Rail Power Control InputOutput Drive Capability—500Ωand 300pF Loads+1V to VCCCurrent Sense Input Common-Mode
Voltage RangeNo Phase-Reversal for Common-Mode Voltage
from 0 to VCCExternal Current Sensing and Gain Setting
Resistors Maximize FlexibilityAvailable in a Space-Saving 8-pin µMAX
MAX4473
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin µMAXypical Operating Circuit19-1448; Rev 0; 3/99
Ordering Information
MAX4473
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin µMAX
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VCC= +2.7V to +6.5V, SHDN> +2.4V, MAX4473 test circuit, RG1 = RG2 = 1kΩ±1%, RG3 = 2.5kΩ±1%, RSENSE= 100Ω±1%, RL
= 10kΩ, CL= 300pF, TA= TMINto TMAX, unless otherwise noted. Typical values are at VCC= +6.0V, VPC= +1.0V, TA= +25°C.)
(Note 1)
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.
VCCto GND...........................................................................+7V
SR1, SR2, SR3, PC, SHDN,
OUT to GND............................................-0.3V to (VCC+ 0.3V)
SR1 to SR3......................................................................0 to VCC
OUT and SR3 Short-Circuit Duration
to VCCor GND........................................................Continuous
Current into Any Pin..........................................................±50mA
Continuous Power Dissipation (TA= +70°C)
µMAX (derate 4.10mW/°C above +70°C).....................330mW
SO (derate 5.88mW/°C above +70°C)..........................471mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10sec).............................+300°C
MAX4473
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin µMAX
ELECTRICAL CHARACTERISTICS (continued)(VCC= +2.7V to +6.5V, SHDN> +2.4V, MAX4473 test circuit, RG1 = RG2 = 1kΩ±1%, RG3 = 2.5kΩ±1%, RSENSE= 100Ω±1%, RL
= 10kΩ, CL= 300pF, TA= TMINto TMAX, unless otherwise noted. Typical values are at VCC= +6.0V, VPC= +1.0V, TA= +25°C.)
(Note 1)
Note 1:Limits over temperature are guaranteed by design.
Note 2:No output phase-reversal for input common-mode voltage range from GND to VCC. Common-mode range limited by voltage
drop across Q1 and RG3.
Note 3:Guaranteed by design.
Note 4:Error dependent on tolerance of RG1, RG2, and RG3. Specified with 0.1% tolerance resistors.
Typical Operating Characteristics(See Test Circuit, TA= +25°C, unless otherwise noted.)
Detailed DescriptionThe MAX4473 is a voltage-controlled, unidirectional,
high-side current setting amplifier for applications
where accurate control of PA supply current is desired.
This device is intended for wireless TDMA based sys-
tems (GSM, DECT), where tight restrictions over the
PA’s transmit burst and output power require closed-
loop control over the PA’s output power. When used
with a PA, the MAX4473 functions as a voltage-con-
trolled constant current source, accurately setting PA
supply current by varying the gain of the PA. If you
know the output power versus supply current profile for
the PA, you can set the PA’s output power by control-
ling the amount of supply current delivered to the PA.
The MAX4473 is composed of an input buffer (A1), a
voltage-to-current converting amplifier (A2), and a rail-
to-rail output error amplifier (A3) (see Typical Operating
Circuit). External gain and sense resistors allow pro-
grammability for a wide range of applications.
In the Typical Operating Circuit, PA supply current
flows from the system supply, through the external cur-
rent sense resistor (RSENSE), to the PA. The rail-to-rail
outputs of the error amplifier, A3, adjust the gain of the
PA until the voltage drop across RSENSEequals the
voltage drop across external gain resistor, RG1. The
voltage drop across RG1 sets the voltage drop across
RSENSE, with a larger voltage drop resulting in more
current delivered to the PA. The voltage drop across
RG1 is set by A1, A2, and the V-to-I FET, Q1. A voltage
applied to the PC input of the input buffer is divided by
four by a resistor-divider network. A2 forces its inverting
input and the source of Q1 to VPC/ 4, thus setting a
voltage across RG3. The resulting current through RG3
sets the current through RG1. This unique architecture
allows the supply current to be set independent of sup-
ply voltage. Set PA supply current according to the fol-
lowing equation:
ICCPA= ( VPC
·RG1 ) / ( 4 ·RSENSE
·RG3 )
Shutdown ModeWhen SHDNis a logic-level low (SHDN< 0.4V), ampli-
fiers A1, A2, and A3 are off, Q1 is turned off, and the
output of A3 is actively pulled to ground with an N-
channel FET. Supply current is reduced to less than
1µA in shutdown mode. Typical power-up time is 0.9µs
and typical power-down time is 0.3µs, using the
MAX4473 test circuit.
Applications Information
Gain Resistor Selection
(RG1, RG2, RG3)For proper operation, do not make the value of external
gain resistors RG1 and RG2 larger than twice the value
of RG3. In most practical applications, choose RG1
smaller than RG3 to limit the voltage drop over RG1
and RSENSE. A large voltage drop over RSENSEsub-
stantially reduces the voltage applied to the PA, thus
reducing PA output power. Set RG2 equal to RG1 to
compensate for the input bias currents of A3.
Recommended values for RG3 are between 1kΩand
10kΩ.
MAX4473
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin µMAX
Pin Description
Sense Resistor Selection (RSENSE)Choose RSENSEbased on the following criteria:
Voltage Loss:A high RSENSEvalue causes the
power-source voltage to degrade through IR loss.
For minimal voltage loss, use low RSENSEvalues.
Accuracy:A high RSENSEvalue allows lower cur-
rents to be measured more accurately because input
offset voltages become less significant when the
sense voltage is larger. For best performance, select
RSENSEto provide approximately 100mV of sense
voltage for the full-scale current in each application.
Efficiency and Power Dissipation:At high current
levels, the I2R losses in RSENSEare significant. Take
this into consideration when choosing the resistor
value and its power dissipation (wattage) rating.
Also, the sense resistor’s value may drift if it is
allowed to heat up excessively.
MAX4473
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin µMAX
_________________________Test Circuit
Pin Configuration
Chip InformationTRANSISTOR COUNT: 348
MAX4473
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin µMAX
Package Information
