MAX8805W Datasheet, PDF (1/22 Pages) Maxim Integrated Products – 600mA/650mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power

19-0777; Rev 1; 10/07
600mA/650mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
General Description
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z
high-frequency step-down converters are optimized for
dynamically powering the power amplifier (PA) in
WCDMA or NCDMA handsets. The devices integrate a
high-efficiency PWM step-down converter for medium-
and low-power transmission, and a 60mΩ typical
bypass FET to power the PA directly from the battery
during high-power transmission. Dual 200mA low-noise,
high-PSRR low-dropout regulators (LDOs) for PA bias-
ing are also integrated.
Two switching frequency options are available (2MHz for
the MAX8805W/MAX8805Y and 4MHz for the MAX8805X/
MAX8805Z), allowing optimization for smallest solution
size or highest efficiency. Fast switching allows the use of
small ceramic 2.2µF input and output capacitors while
maintaining low ripple voltage. The feedback network is
integrated, further reducing external component count
and total solution size.
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z use
an analog input driven by an external DAC to control
the output voltage linearly for continuous PA power
adjustment. The REFIN to OUT gain is available in two
options (2V/V for the MAX8805Y/MAX8805Z and 2.5V/V
for the MAX8805W/MAX8805X). At high-duty cycle, the
MAX8805W/MAX8805X/MAX8805Y/MAX8805Z auto-
matically switch to the bypass mode, connecting the
input to the output through a low-impedance (60mΩ
typ) MOSFET. The user can also enable the bypass
mode directly through a logic-control input.
The LDOs in the MAX8805W/MAX8805X/MAX8805Y/
MAX8805Z are designed for low-noise operation
(35µV_RMS typ). Each LDO is individually enabled
through its own logic control interface.
The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z are
available in a 16-bump, 2mm x 2mm WLP package
(0.7mm max height).
Features
♦ PA Step-Down Converter
7.5µs (typ) Settling Time for 0.8V to 3.4V Output
Voltage Change
Dynamic Output Voltage Setting from 0.4V to
V_BATT
60mΩ pFET and 100% Duty Cycle for Low
Dropout
2MHz or 4MHz Switching Frequency
Low Output-Voltage Ripple
600mA (MAX8805Y/MAX8805Z) or 650mA
(MAX8805W/MAX8805X) Output Drive
Capability
2% Maximum Accuracy
Tiny External Components
♦ Dual Low-Noise LDOs
Low 35µV_RMS (typ) Output Noise
High 70dB (typ) PSRR
Guaranteed 200mA Output Drive Capability
Individual ON/OFF Control
♦ Low 0.1µA Shutdown Current
♦ 2.7V to 5.5V Supply Voltage Range
♦ Thermal Shutdown
♦ Tiny 2mm x 2mm x 0.7mm WLP Package
(4 x 4 Grid)
Applications
WCDMA/NCDMA Cellular Handsets
Wireless PDAs
Smartphones
Pin Configuration appears at end of data sheet.
Ordering Information
PART
PIN-
PACKAGE
PKG
CODE
MAX8805WEWExy+T*
16 WLP-16
W162B2+1
MAX8805XEWExy+T*
16 WLP-16
W162B2+1
MAX8805YEWExy+T*
16 WLP-16
W162B2+1
MAX8805ZEWExy+T*
16 WLP-16
W162B2+1
+Denotes a lead-free package.
T = Tape and reel package.
*xy is the output voltage code (see Table 1).
Note: All devices are specified over the -40°C to +85°C operating temperature range.
SWITCHING
FREQUENCY
2MHz
4MHz
2MHz
4MHz
REFIN TO OUT GAIN
2.5V/V
2.5V/V
2V/V
2V/V
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