MAX4473_08 [MAXIM]
Low-Cost, Low-Voltage, PA Power Control Amplifier for GSM Applications; 低成本，低电压， PA功率控制放大器，用于GSM应用
| 型号： | MAX4473_08 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Low-Cost, Low-Voltage, PA Power Control Amplifier for GSM Applications |
| 文件： | 总9页 (文件大小：198K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1448; Rev 4; 11/08
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
MAX473
General Description
Features
The 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) through a control volt-
age. 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.
♦ Optimized for GSM Timing Requirements
♦ 2.7V to 6.5V Single-Supply Operation
♦ 1.2mA Supply Current
♦ ≤ 1µA Supply Current in Shutdown Mode
♦ Guaranteed 1.5µs Enable/Disable Times
♦ Active Output Pull-Down in Shutdown Mode
♦ Rail-to-Rail Error Amplifier Output
♦ Rail-to-Rail Power Control Input
♦ Output Drive Capability—500Ω and 300pF Loads
The MAX4473 operates from a single 2.7V to 6.5V sup-
ply and typically draws 1.2mA of supply current. The
error amplifier has a common-mode range that extends
♦ 1V to V
Current Sense Input Common-Mode
CC
Voltage Range
♦ No Phase-Reversal for Common-Mode Voltage
from 1V to V . The power control input and error
CC
from 0 to V
CC
amplifier outputs swing rail-to-rail. A low-power shut-
down 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 compro-
mising dynamic performance. The MAX4473 is avail-
able in a space-saving 8-pin µMAX® package.
♦ External Current Sensing and Gain Setting
Resistors Maximize Flexibility
♦ Available in a Space-Saving 8-Pin µMAX
Ordering Information
Applications
GSM Cellular Phones
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
MAX4473EUA
MAX4473ESA
Cordless Phones
8 SO
Precision Current Control
Pin Configuration appears at end of data sheet.
High-Frequency Servo Loops
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Typical Operating Circuit
V
CC
R
0.1μF
SENSE
RG1
RG2
A3
8
V
1
SR1
2
SR2
4
3
CC
PC
7
OUT
I
CCPA
A1
BUFFER
GC
IN
V-TO-I
CONVERTER
3R
R
ERROR
AMPLIFIER
V
CC
PA
Q1
A2
MAX4473
SHDN
GND
5
SR3
RFIN
V
· RG1
PC
6
I
=
CCPA
4 · RG3 · R
RG3
SENSE
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND..............................................................................7V
Continuous Power Dissipation (T = +70°C)
A
SR1, SR2, SR3, PC, SHDN,
OUT to GND ............................................-0.3V to (V
SR1 to SR3......................................................................0 to V
OUT and SR3 Short-Circuit Duration
8-Pin µMAX (derate 4.10mW/°C above +70°C)............330mW
8-Pin 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, 10s) .................................+300°C
+ 0.3V)
CC
CC
to V
or GND ........................................................Continuous
CC
Current into Any Pin.......................................................... 50mA
MAX473
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
(V
= 2.7V to 6.5V, SHDN > 2.4V, MAX4473 test circuit, RG1 = RG2 = 1kΩ 1ꢀ, RG3 = 2.5kΩ 1ꢀ, R
= 100Ω 1ꢀ,
SENSE
CC
R = 10kΩ, C = 300pF, T = T
to T , unless otherwise noted. Typical values are at V = 6.0V, V = 1.0V, T = +25°C.) (Note 1)
MAX CC PC A
L
L
A
MIN
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
GENERAL
Supply Voltage
Supply Current
2.7
2.4
6.5
2
V
mA
µA
V
V
= 0
1.2
PC
Shutdown Supply Current
SHDN < 0.4V, R = 10Ω
0.03
1
L
SHDN Input High Voltage
SHDN Input Low Voltage
SHDN Input Current
ERROR AMPLIFIER
0.4
0.5
V
SHDN = 0 to V
µA
CC
1V < V
1V < V
, V
< V
< V
0.5
0.5
2
1
SR1 SR2
CC
CC
SR1, SR2 Input Offset Voltage
mV
, V
SR1 SR2
at +25°C
SR1, SR2 Input Offset Voltage
Drift
10
1V < V
, V
SR1 SR2
< V
µV/°C
CC
SR1, SR2 Input Common-Mode
Voltage Range
Inferred from CMRR test; V
= GND (Note 2)
1
V
V
SR2
CC
1
SR1, SR2 Input Bias Current
1V < V
1V < V
, V
< V , V = GND, SR3 = unconnected
0.04
µA
µA
SR1 SR2
CC PC
SR1, SR2 Input Bias Offset
Current
, V
SR1 SR2
< V , V = GND, SR3 = unconnected
0.001
0.2
0.5
CC PC
SR1, SR2 Shutdown Leakage
Current
SHDN < 0.4V, V
= V
= V
CC
0.001
µA
SR1
SR2
V
V
= 2.7V
= 6.5V
65
75
80
80
80
80
80
85
95
CC
CC
1V < V
, V
< V
,
CC
SR1 SR2
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
dB
dB
V
= GND
PC
2.7V < V
< 6.5V, V = GND
90
CC
PC
V
V
V
V
= 6.5V, 0.3V < V
< 6V
130
125
130
120
CC
CC
CC
CC
OUT
OUT
OUT
OUT
R = 10kΩ to V
L
/ 2
/ 2
CC
= 2.7V, 0.3V < V
= 6.5V, 0.7V < V
= 2.7V, 0.7V < V
< 2.4V
< 5.5V
< 2.2V
Large-Signal Gain
dB
R = 500Ω to V
L
CC
2
_______________________________________________________________________________________
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
MAX473
ELECTRICAL CHARACTERISTICS (continued)
(V
= 2.7V to 6.5V, SHDN > 2.4V, MAX4473 test circuit, RG1 = RG2 = 1kΩ 1ꢀ, RG3 = 2.5kΩ 1ꢀ, R
= 100Ω 1ꢀ,
SENSE
CC
R = 10kΩ, C = 300pF, T = T
to T , unless otherwise noted. Typical values are at V = 6.0V, V = 1.0V, T = +25°C.) (Note 1)
MAX CC PC A
L
L
A
MIN
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
0.15
-
CC
R = 10Ω to V
/ 2
0.15
0.5
L
CC
Output Voltage Swing
Output Current Limit
V
V
0.5
-
CC
R = 500Ω to V
L
/ 2
CC
V
= V
/ 2
CC
20
2
mA
MHz
OUT
Gain-Bandwidth Product
Phase Margin
R = 10Ω, C = 300pF, f = 10kHz
L L o
R = 10Ω, C = 300pF
60
degrees
L
L
Measured from 30ꢀ to 70ꢀ of V
,
OUT
Slew Rate
1.8
V/µs
R = 10Ω, C = 300pF
L
L
Capacitive-Load Stability
Enable/Disable Time
No sustained oscillations (Note 3)
From 50ꢀ of SHDN edge to V
0
300
1.5
pF
µs
= 1V, V = 2V
0.9
OUT
PC
GAIN CONTROL BUFFER AND V-TO-I CONVERTER
PC Input Bias Current
GND < V < V
- 0.15V
CC
0.04
4
1
µA
PC
SR3 Output Current Limit
V
< 2.55V, SR1 = SR2 = V
0.750
0.095
mA
PC
CC
Measure voltage across RG1,
0.3V < V < 2.55V (Note 4)
V
to VRG1 Ratio
0.1
2
0.105
V/V
PC
PC
PC Input Bandwidth
Bandwidth from V to V
MHz
PC
RG1
Note 1: Limits over temperature are guaranteed by design.
Note 2: No output phase-reversal for input common-mode voltage range from GND to V . Common-mode range limited by voltage
CC
drop across Q1 and RG3.
Note 3: Guaranteed by design.
Note 4: Error dependent on tolerance of RG1, RG2, and RG3. Specified with 0.1ꢀ tolerance resistors.
_______________________________________________________________________________________
3
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
Typical Operating Characteristics
(See Test Circuit, T = +25°C, unless otherwise noted.)
A
V
RG1
/ V RATIO vs. V RESPONSE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
PC
PC
1.4
0.1100
0.1075
0.1050
0.1025
0.1000
0.0975
0.0950
0.0925
0.0900
V
CC
= 6.0V
T
= -40°C
A
1.2
1.0
0.8
0.6
0.4
T
A
= +25°C
MAX473
T
A
= +85°C
SHDN = V
PC = GND
CC
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
SUPPLY VOLTAGE (V)
0
1
2
3
4
5
6
V
(V)
PC
ERROR-AMPLIFIER RESPONSE
ENABLE/DISABLE TIME
MAX4473 toc03
70
0
A
V
V
V
= 1000
= 6.5V
VCL
60
50
40
30
-18
-36
-54
-72
CC
CM
PC
= V / 2
CC
SHDN
2V/div
= 0
GND
V
V
= 6.5V
= 2V
CC
PC
GAIN
PHASE
ERROR
20
10
-90
-108
-126
-144
-162
AMPLIFIER
0
100kΩ
10kΩ
-10
-20
300pF
OUT
500mV/div
GND
100Ω
-30
-180
10M
10
100
1k
10k
100k
1M
500ns/div
FREQUENCY (Hz)
ERROR-AMPLIFIER
OUTPUT LOW VOLTAGE vs. TEMPERATURE
ERROR-AMPLIFIER
OUTPUT HIGH VOLTAGE vs. TEMPERATURE
0.30
0.25
0.20
0.15
0.10
0.05
0
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
V
= 6.5V, R = 500Ω to V / 2
L CC
CC
V
= 6.5V, R = 500Ω to V / 2
L CC
CC
V
CC
= 2.7V, R = 500Ω to V / 2
L CC
V
= 2.7V, R = 500Ω to V / 2
CC
L
CC
V
= 6.5V, R = 10kΩ to V / 2
L CC
CC
V
CC
= 2.7V, R = 10kΩ to V / 2
L CC
V
= 6.5V, R = 10kΩ to V / 2
CC
L
CC
V
CC
= 2.7V, R = 10kΩ to V / 2
L CC
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
MAX473
Pin Description
PIN
NAME
FUNCTION
Inverting Input of Error Amplifier and Drain of V-to-I FET, Q1. Connect to supply side of current-sense
1
SR1
resistor, R , through gain resistor RG1.
SENSE
Noninverting Input of Error Amplifier. Connect to load side of current-sense resistor, R
gain resistor RG2. Set RG2 equal to RG1.
, through
SENSE
2
3
4
SR2
SHDN
PC
Shutdown Input. Drive SHDN low to disable all amplifiers, pull OUT to GND, set the gate-to-source
voltage of the V-to-I FET (Q1) to 0, and reduce supply current to less than 1µA. Drive high or connect
to V
for normal operation.
CC
Power Control Input. Apply a voltage to PC to set a DC current through the sense resistor to control
PA bias.
5
6
GND
SR3
Ground
Inverting Input to V-to-I Converter and Source of V-to-I FET, Q1. Connect to ground through gain
resistor RG3.
7
8
OUT
VCC
Output of Error Amplifier. Connect to gain control pin of power amplifier in bias control applications.
+2.7V to +6.5V Voltage Supply Input. Bypass to ground with a 0.1µF capacitor.
PA until the voltage drop across R
equals the
SENSE
Detailed Description
voltage drop across external gain resistor, RG1. The
The 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.
voltage drop across RG1 sets the voltage drop across
R
, with a larger voltage drop resulting in more
SENSE
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 V
/ 4, thus setting a
PC
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:
I
= ( V · RG1 ) / ( 4 · R
· RG3 )
CCPA
PC
SENSE
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.
Shutdown Mode
When SHDN is 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.
In the Typical Operating Circuit, PA supply current
flows from the system supply, through the external cur-
rent-sense resistor (R
), to the PA. The rail-to-rail
SENSE
outputs of the error amplifier, A3, adjust the gain of the
_______________________________________________________________________________________
5
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
• Accuracy: A high R
value allows lower cur-
SENSE
Applications Information
rents to be measured more accurately because input
offset voltages become less significant when the
sense voltage is larger. For best performance, select
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
R
to provide approximately 100mV of sense
SENSE
voltage for the full-scale current in each application.
• Efficiency and Power Dissipation: At high current
levels, the I2R losses in R
are significant. Take
SENSE
and R
. A large voltage drop over R
sub-
SENSE
SENSE
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.
MAX473
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 1kΩ and
10kΩ.
Sense Resistor Selection (R
)
SENSE
Choose R
based on the following criteria:
SENSE
• Voltage Loss: A high R
value causes the
SENSE
power-source voltage to degrade through IR loss.
For minimal voltage loss, use low R values.
SENSE
Pin Configuration
_________________________Test Circuit
TOP VIEW
R
SENSE
V
CC
100Ω
0.1%
RG1
1kΩ
1%
RG2
1kΩ
1%
0.1μF
SR1
SR2
1
2
3
4
8
7
6
5
V
CC
V
SR1
SR2
CC
OUT
SR3
GND
MAX4473
PC
2N3904
OUT
MAX4473
SHDN
PC
C
300pF
L
R
L
SHDN
GND
10kΩ
SR3
RG3
R
E
750Ω
μMAX/SO
2.5kΩ
1%
Chip Information
TRANSISTOR COUNT: 348
6
_______________________________________________________________________________________
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
MAX473
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PACKAGE TYPE
8 µMAX
PACKAGE CODE
DOCUMENT NO.
21-0036
U8-1
8 SO
S8-2
21-0041
α
α
_______________________________________________________________________________________
7
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
INCHES
MILLIMETERS
DIM
A
MIN
MAX
0.069
0.010
0.019
0.010
MIN
1.35
0.10
0.35
0.19
MAX
1.75
0.25
0.49
0.25
0.053
0.004
0.014
0.007
N
A1
B
MAX473
C
e
0.050 BSC
1.27 BSC
E
0.150
0.228
0.016
0.157
0.244
0.050
3.80
5.80
0.40
4.00
6.20
1.27
E
H
H
L
VARIATIONS:
INCHES
1
MILLIMETERS
DIM
D
MIN
MAX
0.197
0.344
0.394
MIN
4.80
8.55
9.80
MAX
5.00
N
8
MS012
AA
TOP VIEW
0.189
0.337
0.386
D
8.75 14
10.00 16
AB
D
AC
D
C
A
B
0∞-8∞
e
A1
L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL
DOCUMENT CONTROL NO.
REV.
1
21-0041
B
1
8
_______________________________________________________________________________________
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications
MAX473
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
4
11/08
Removed QFN package
1–9
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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