MAX8896 Datasheet, PDF (1/17 Pages) Maxim Integrated Products – Dual PWM Step-Down Converter in a 2mm x 2mm Package for WCDMA PA and RF Power

19-4663; Rev 0; 5/09
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 (16µV_RMS,
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
V_BATT
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 (16µV_RMS, 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
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