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PDF MAX8896 Data sheet ( Hoja de datos )
| Número de pieza | MAX8896 | |
| Descripción | Dual PWM Step-Down Converter | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX8896 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
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19-4663; Rev 0; 5/09
www.DataSheet4U.com
Dual PWM Step-Down Converter in a 2mm x
2mm Package for WCDMA PA and RF Power
General Description
The MAX8896 dual step-down converter is optimized
for powering the power amplifier (PA) and RF transceiv-
er in WCDMA handsets. This device integrates a high-
efficiency PWM step-down converter (OUT1) for
medium and low-power transmission, and a 140mΩ
(typ) bypass FET to power the PA directly from the bat-
tery during high-power transmission. A second high-
efficiency PWM step-down converter (OUT2) supplies
power directly to a high PSRR, low output noise, 200mA
low-dropout linear regulator (LDO) to power the RF
transceiver.
Fast switching allows the use of small ceramic input and
output capacitors while maintaining low ripple voltage.
The feedback network is integrated reducing external
component count and total solution size. OUT1 uses an
analog input driven by an external DAC to control the
output voltage linearly for continuous PA power adjust-
ment. At high duty cycle, OUT1 automatically switches to
bypass mode, connecting the input to the output through
a low-impedance (140mΩ, typ) MOSFET.
OUT2 is a 2MHz fixed-frequency, step-down converter
capable of operating at 100% duty cycle. Output accu-
racy is ±2% over load, line, and temperature. The out-
put of OUT2 is preset to 3.1V to provide power to a
200mA, 2.8V LDO designed for low noise (16µVRMS,
typ), high PSRR (65dB, typ) operation. This configura-
tion provides noise attenuation for the RF transceiver
power supply in the 100Hz to 100kHz range.
Other features include separate output enables, low-
supply current shutdown, output overcurrent, and
overtemperature protection. The MAX8896 is available
in a 16-bump, 2mm x 2mm UCSP™ package (0.7mm
max height).
Applications
WCDMA/NCDMA Cellular Handsets
Smartphones
Features
o PA Step-Down Converter (OUT1)
7.5µs (typ) Settling Time for 0.5V to 1V Output
Voltage Change
Dynamic Output Voltage Setting from 0.5V to
VBATT
140mΩ Bypass PFET and 100% Duty Cycle
for Low Dropout
2MHz Switching Frequency
Low Output Voltage Ripple
700mA (min) Output Drive Capability
2% Gain Accuracy
Tiny External Components
o RF Step-Down Converter (OUT2)
2MHz Fixed Switching Frequency
94% Peak Efficiency
100% Duty Cycle
2% Output Accuracy Over Load, Line, and
Temperature
200mA (min) Output Drive Capability
Tiny External Components
o Low-Noise LDO
Guaranteed 200mA Output
High 65dB (typ) PSRR
Fixed Output Voltage
Low Noise (16µVRMS, typ)
o Simple Logic ON/OFF Controls
o Low 0.1µA Shutdown Current
o 2.7V to 5.5V Supply Voltage Range
o Thermal Shutdown
o 2mm x 2mm UCSP Package (4 x 4 Grid)
Ordering Information
PART
PIN-PACKAGE
LDO
VOLTAGE
MAX8896EREE+T 16 UCSP (0.5mm pitch)
2.80V
Note: Device operates over the -40°C to +85°C temperature
range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
UCSP is a trademark of Maxim Integrated Products, Inc.
Pin Configurations appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For information on other Maxim products, visit Maxim’s website at www.maxim-ic.com.
1 page  
www.DataSheet4U.com
Dual PWM Step-Down Converter in a 2mm x
2mm Package for WCDMA PA and RF Power
Typical Operating Characteristics
(VCC = VIN1 = VIN2 = 3.6V, VREFIN = 0.72V, circuit of Figure 3, TA = +25°C, unless otherwise noted.)
OUT1 PA BYPASS MODE DROPOUT
VOLTAGE vs. PA LOAD CURRENT
80
70 VIN1 = 3.2V
60 VIN1 = 3.6V
50
40
VIN1 = 4.2V
30
20
10
0
0 100 200 300 400 500 600 700
LOAD CURRENT (mA)
OUT1 PA STEP-DOWN CONVERTER
EFFICIENCY vs. LOAD CURRENT
VPA = 2.58V
100
OUT1 PA STEP-DOWN CONVERTER
EFFICIENCY vs. OUTPUT VOLTAGE
100
90
80 BYPASS MODE
70 VIN1 = 4.2V
60 VIN1 = 3.6V
50 VIN1 = 3.2V
40
30
20
10 RPA = 7.5Ω
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
OUTPUT VOLTAGE (V)
OUT1 PA STEP-DOWN CONVERTER
EFFICIENCY vs. LOAD CURRENT
VPA = 1.58V
100
OUT1 PA STEP-DOWN CONVERTER
EFFICIENCY vs. LOAD CURRENT
VPA = 3.18V
100
95
90
85
80
75
70
100
200 300 400 500 600
LOAD CURRENT (mA)
700
OUT1 PA STEP-DOWN CONVERTER
EFFICIENCY vs. LOAD CURRENT
VPA = 1.18V
100
95 95
95
90 90
90
85 85
85
80 80
80
75 75
75
70
50
150 250 350 450 550 650
LOAD CURRENT (mA)
OUT1 PA STEP-DOWN CONVERTER
EFFICIENCY vs. LOAD CURRENT
VPA = 0.77V
100
95
90
85
80
75
70
65
60
25
75 125 175
LOAD CURRENT (mA)
225
70
50
150 250 350
LOAD CURRENT (mA)
450
OUT1 PA STEP-DOWN CONVERTER
EFFICIENCY vs. LOAD CURRENT
VPA = 0.56V
100
95
90
85
80
75
70
65
60
25
75 125 175
LOAD CURRENT (mA)
225
70
50
150
LOAD CURRENT (mA)
250
OUT1 PA STEP-DOWN CONVERTER
OUTPUT VOLTAGE vs. LOAD CURRENT
1.90
1.88 RL = 0.09Ω
1.86
1.84
1.82
1.80
1.78
1.76
1.74
1.72
1.70
0
100 200 300 400 500 600 700
LOAD CURRENT (mA)
_______________________________________________________________________________________ 5
5 Page 
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Dual PWM Step-Down Converter in a 2mm x
2mm Package for WCDMA PA and RF Power
IN1
VCC
AGND
REFIN
REFBP
PAEN
RFEN1
RFEN2
R4 R5
BYPASS FET
BIAS
R7
R6 C2
CURRENT-LIMIT
CONTROL
PWM ERROR
COMPARATOR
OUT1
PWM LOGIC
OUT1
EN
EN
STEP DOWN
CURRENT LIMIT
C1 R3
R2 R1
VCC
1.25V
REFERENCE
BANDGAP
OUT1
EN
CONTROL
LOGIC
BANDGAP
ERROR
AMP
LDO
CURRENT LIMIT
OUT2
EN PWM LOGIC
BANDGAP
FB NETWORK/
COMPENSATION
PA OUT
LX1
PGND1
OUT2
LDO
R9
R7
IN2
LX2
PGND2
OUT2
Figure 1. Block Diagram
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet MAX8896.PDF ] | |
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