MAX4473EGA [MAXIM]
Industrial Control IC ; 工业控制IC\n
| 型号： | MAX4473EGA |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Industrial Control IC
|
| 文件： | 总7页 (文件大小：297K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1448; Rev 1; 1/02
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin QFN
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—500 and 300pF Loads
ꢀ 1V to V
Current Sense Input Common-Mode
CC
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
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 QFN package.
ꢀ External Current Sensing and Gain Setting
Resistors Maximize Flexibility
ꢀ Available in a Space-Saving 8-Pin QFN
Ordering Information
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
Applications
GSM Cellular Phones
MAX4473EUA
MAX4473EGA
MAX4473ESA
8 QFN
Cordless Phones
8 SO
Precision Current Control
Pin Configuration appears at end of data sheet.
High-Frequency Servo Loops
Typical Operating Circuit
V
CC
R
0.1 F
SENSE
RG1
RG2
A3
8
1
SR1
2
SR2
V
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
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
________________________________________________________________ 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 in 8-Pin QFN
ABSOLUTE MAXIMUM RATINGS
CC
V
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 4.10ꢁW/°C above +70°C)............330ꢁW
8-Pin QFN (derate 24.4ꢁW/°C above +70°C) ............1951ꢁW
8-Pin SO (derate 5.88ꢁW/°C above +70°C).................471ꢁW
Operating Teꢁperature Range ...........................-40°C to +85°C
Junction Teꢁperature......................................................+150°C
Storage Teꢁperature Range.............................-65°C to +150°C
Lead Teꢁperature (soldering, 10s) .................................+300°C
+ 0.3V)
CC
CC
to V
or GND ........................................................Continuous
CC
Current into Any Pin.......................................................... 50ꢁA
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 = 1k
1ꢀ, RG3 = 2.5k 1ꢀ, R
, unless otherwise noted. Typical values are at V = 6.0V, V
CC PC
= 100
1ꢀ,
CC
SENSE
R
= 10k , C = 300pF, T = T
to T
= 1.0V, T = +25°C.)
L
L
A
MIN
MAX
A
(Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
GENERAL
Supply Voltage
2.7
2.4
6.5
2
V
ꢁA
µA
V
Supply Current
V
= 0
1.2
PC
Shutdown Supply Current
SHDN Input High Voltage
SHDN Input Low Voltage
SHDN Input Current
ERROR AMPLIFIER
0.03
1
SHDN < 0.4V, R = 10k
L
0.4
0.5
V
µA
SHDN = 0 to V
CC
SR1, SR2 Input Offset Voltage
1V < V
1V < V
, V
< V
< V
0.5
10
2
ꢁV
SR1 SR2
CC
SR1, SR2 Input Offset Voltage Drift
, V
SR1 SR2
µV/ C
CC
SR1, SR2 Input Coꢁꢁon-Mode
Voltage Range
Inferred froꢁ CMRR test; V = GND (Note 2)
1
V
CC
V
PC
1V < V
SR3 = unconnected
, V
< V , V = GND,
SR1 SR2 CC PC
SR1, SR2 Input Bias Current
0.04
1
µA
1V < V , V < V , V = GND,
SR3 = unconnected
SR1 SR2
CC PC
SR1, SR2 Input Bias Offset Current
SR1, SR2 Shutdown Leakage Current
Coꢁꢁon-Mode Rejection Ratio
Power-Supply Rejection Ratio
0.001
0.2
0.5
µA
µA
dB
dB
0.001
85
95
SHDN < 0.4V, V
= V
= V
CC
SR1
SR2
V
V
= 2.7V
= 6.5V
65
75
1V < V
, V
< V
,
CC
SR1 SR2
CC
V
PC
= GND
CC
2.7V < V < 6.5V, V = GND
80
90
CC
PC
V
CC
V
CC
V
CC
V
CC
= 6.5V, 0.3V < V
= 2.7V, 0.3V < V
= 6.5V, 0.7V < V
= 2.7V, 0.7V < V
< 6V
80
80
80
80
130
125
130
120
R = 10k
OUT
OUT
OUT
OUT
L
to V
/ 2
CC
< 2.4V
< 5.5V
< 2.2V
Large-Signal Gain
dB
R = 500
L
to V
/ 2
CC
R = 10k to V
/ 2
/ 2
0.15
0.5
V
V
-
0.15
CC
-
0.5
CC
L
CC
Output Voltage Swing
V
R = 500 to V
L
CC
Output Current Liꢁit
Gain-Bandwidth Product
Phase Margin
V
= V
/ 2
20
2
ꢁA
MHz
OUT
CC
R = 10k , C = 300pF, f = 10kHz
L
L
o
R = 10k , C = 300pF
60
degrees
L
L
Measured froꢁ 30ꢀ to 70ꢀ of V
C = 300pF
L
, R = 10k ,
L
OUT
Slew Rate
1.8
V/µs
2
_______________________________________________________________________________________
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin QFN
ELECTRICAL CHARACTERISTICS (continued)
(V
= 2.7V to 6.5V, SHDN > 2.4V, MAX4473 test circuit, RG1 = RG2 = 1k
1ꢀ, RG3 = 2.5k 1ꢀ, R
, unless otherwise noted. Typical values are at V = 6.0V, V
CC PC
= 100
1ꢀ,
CC
SENSE
R
= 10k , C = 300pF, T = T
to T
= 1.0V, T = +25°C.)
L
L
A
MIN
MAX
A
(Note 1)
PARAMETER
CONDITIONS
No sustained oscillations (Note 3)
Froꢁ 50ꢀ of SHDN edge to V
MIN
TYP
MAX
300
1.5
UNITS
pF
Capacitive-Load Stability
Enable/Disable Tiꢁe
0
0.9
µs
= 1V, V = 2V
OUT
PC
GAIN CONTROL BUFFER AND V-TO-I CONVERTER
PC Input Bias Current
GND < V < V
- 0.15V
0.04
4
1
µA
ꢁA
PC
CC
SR3 Output Current Liꢁit
V
PC
= 2.55V, SR1 = SR2 = V
0.750
0.095
CC
V
PC
to V
Ratio
Measure voltage across RG1, 0.3V < V < 2.55V (Note 4)
0.1
2
0.105
V/V
RG1
PC
PC Input Bandwidth
Bandwidth froꢁ V to V
MHz
PC
RG1
Note 1: Liꢁits over teꢁperature are guaranteed by design.
Note 2: No output phase-reversal for input coꢁꢁon-ꢁode voltage range froꢁ GND to V . Coꢁꢁon-ꢁode range liꢁited 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.
Typical Operating Characteristics
(See Test Circuit, T = +25°C, unless otherwise noted.)
A
V
/ V RATIO vs. V RESPONSE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
ERROR-AMPLIFIER RESPONSE
MAX4473 toc03
RG1
PC
PC
0.1100
0.1075
0.1050
0.1025
0.1000
0.0975
0.0950
0.0925
0.0900
70
60
50
40
30
0
1.4
1.2
1.0
0.8
0.6
0.4
A
V
V
V
= 1000
VCL
V
= 6.0V
CC
-18
-36
-54
-72
T
= -40 C
= 6.5V
A
CC
CM
PC
= V / 2
CC
T
= +25 C
A
= 0
GAIN
PHASE
ERROR
T
= +85 C
A
20
10
-90
-108
-126
-144
-162
AMPLIFIER
0
100k
100
10k
-10
-20
300pF
SHDN = V
PC = GND
CC
-30
-180
10
100
1k
10k
100k
1M
10M
0
1
2
3
4
5
6
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
SUPPLY VOLTAGE (V)
FREQUENCY (Hz)
V
(V)
PC
ERROR-AMPLIFIER
OUTPUT LOW VOLTAGE vs. TEMPERATURE
ERROR-AMPLIFIER
OUTPUT HIGH VOLTAGE vs. TEMPERATURE
ENABLE/DISABLE TIME
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 = 500 to V / 2
L CC
CC
V
= 6.5V, R = 500 to V / 2
L CC
CC
SHDN
2V/div
GND
GND
V
V
= 6.5V
= 2V
CC
PC
V
= 2.7V, R = 500 to V / 2
L CC
CC
V
= 2.7V, R = 500 to V / 2
CC
L
CC
V
= 6.5V, R = 10k to V / 2
L CC
CC
V
= 2.7V, R = 10k to V / 2
L CC
CC
OUT
500mV/div
V
= 6.5V, R = 10k to V / 2
CC
L
CC
V
= 2.7V, R = 10k to V / 2
L CC
CC
-40
-15
10
35
60
85
-40
-15
10
35
60
85
500ns/div
TEMPERATURE ( C)
TEMPERATURE ( C)
_______________________________________________________________________________________
3
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin QFN
Pin Description
PIN
NAME
FUNCTION
Inverting Input of Error Aꢁplifier and Drain of V-to-I FET, Q1. Connect to supply side of current-sense resis-
SR1
1
tor, R , through gain resistor RG1.
SENSE
Noninverting Input of Error Aꢁplifier. Connect to load side of current-sense resistor, R
resistor RG2. Set RG2 equal to RG1.
, through gain
SENSE
2
3
SR2
Shutdown Input. Drive SHDN low to disable all aꢁplifiers, 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
SHDN
for nor-
CC
ꢁal operation.
4
5
PC
Power Control Input. Apply a voltage to PC to set a DC current through the sense resistor to control PA bias.
Ground
GND
Inverting Input of V-to-I Converter and Source of V-to-I FET, Q1. Connect to ground through gain resistor
RG3.
6
SR3
7
8
OUT
Output of Error Aꢁplifier. Connect to gain control pin of power aꢁplifier in bias control applications.
+2.7V to +6.5V Voltage Supply Input. Bypass to ground with a 0.1µF capacitor.
V
CC
four by a resistor-divider network. A2 forces its inverting
Detailed Description
input and the source of Q1 to V
/ 4, thus setting a
PC
The MAX4473 is a voltage-controlled, unidirectional,
high-side current setting aꢁplifier for applications
where accurate control of PA supply current is desired.
This device is intended for wireless TDMA based sys-
teꢁs (GSM, DECT), where tight restrictions over the
PA’s transꢁit 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 aꢁount of supply current delivered to the PA.
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
Shutdown Mode
When SHDN is a logic-level low (SHDN < 0.4V), aꢁpli-
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 ꢁode. Typical power-up tiꢁe is 0.9µs
and typical power-down tiꢁe is 0.3µs, using the
MAX4473 test circuit.
The MAX4473 is coꢁposed of an input buffer (A1), a
voltage-to-current converting aꢁplifier (A2), and a rail-
to-rail output error aꢁplifier (A3) (see Typical Operating
Circuit). External gain and sense resistors allow pro-
graꢁꢁability for a wide range of applications.
Applications Information
Gain Resistor Selection
(RG1, RG2, RG3)
In the Typical Operating Circuit, PA supply current
For proper operation, do not ꢁake the value of external
gain resistors RG1 and RG2 larger than twice the value
of RG3. In ꢁost practical applications, choose RG1
sꢁaller than RG3 to liꢁit the voltage drop over RG1
flows froꢁ the systeꢁ supply, through the external cur-
rent-sense resistor (R
), to the PA. The rail-to-rail
SENSE
outputs of the error aꢁplifier, A3, adjust the gain of the
PA until the voltage drop across R equals the
SENSE
and R
. A large voltage drop over R
sub-
SENSE
SENSE
voltage drop across external gain resistor, RG1. The
voltage drop across RG1 sets the voltage drop across
stantially reduces the voltage applied to the PA, thus
reducing PA output power. Set RG2 equal to RG1 to
coꢁpensate for the input bias currents of A3.
Recoꢁꢁended values for RG3 are between 1k and
10k .
R
, with a larger voltage drop resulting in ꢁore
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
4
_______________________________________________________________________________________
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin QFN
Efficiency and Power Dissipation: At high current
Sense Resistor Selection (R
)
SENSE
levels, the I2R losses in R
are significant. Take
Choose R
based on the following criteria:
SENSE
SENSE
this into consideration when choosing the resistor
value and its power dissipation (wattage) rating.
Also, the sense resistor’s value ꢁay drift if it is
allowed to heat up excessively.
Voltage Loss: A high R
power-source voltage to degrade through IR loss.
For ꢁiniꢁal voltage loss, use low R values.
value causes the
SENSE
SENSE
Accuracy: A high R
value allows lower cur-
SENSE
rents to be ꢁeasured ꢁore accurately because input
offset voltages becoꢁe less significant when the
sense voltage is larger. For best perforꢁance, select
R
to provide approxiꢁately 100ꢁV of sense
SENSE
voltage for the full-scale current in each application.
_________________________Test Circuit
Pin Configuration
R
SENSE
TOP VIEW
V
CC
100
0.1%
RG1
1k
1%
RG2
1k
1%
0.1 F
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
L
300pF
R
10k
L
SHDN
GND
SR3
R
750
E
RG3
2.5k
1%
QFN/ MAX/SO
Chip Information
TRANSISTOR COUNT: 348
_______________________________________________________________________________________
5
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin QFN
Package Information
6 _________________________________________________________________________________________
Low-Cost, Low-Voltage, PA Power Control
Amplifier for GSM Applications in 8-Pin QFN
Package Information (continued)
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 ______________________7
© 2002 Maxiꢁ Integrated Products
Printed USA
is a registered tradeꢁark of Maxiꢁ Integrated Products.
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