MAX8805Y Datasheet, PDF (1/21 Pages) Maxim Integrated Products – 600mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power

19-0777; Rev 0; 4/07
600mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
General Description
The 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 biasing are also integrated.
Two switching frequency options are available—2MHz
(MAX8805Y) and 4MHz (MAX8805Z)—allowing optimiza-
tion 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 MAX8805Y/MAX8805Z use an analog input driven
by an external DAC to control the output voltage linearly
for continuous PA power adjustment. At high duty
cycle, the MAX8805Y/MAX8805Z automatically 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 MAX8805Y/MAX8805Z are designed
for low-noise operation (35µV_RMS typ). Each LDO is indi-
vidually enabled through its own logic control interface.
The MAX8805Y/MAX8805Z are available in a 16-bump,
2mm x 2mm WLP package (0.7mm max height).
Applications
WCDMA/NCDMA Cellular Handsets
Wireless PDAs
Smartphones
Ordering Information
PART
PIN-
PACKAGE
PKG
CODE
SWITCHING
FREQUENCY
(MHz)
MAX8805YEWExy+T* 16 WLP-16 W162B2+1
2
MAX8805ZEWExy+T* 16 WLP-16 W162B2+1
4
+Denotes a lead-free package.
T = Tape and reel package.
*xy is the output voltage code (see Table 1 in the Output
Voltages section).
Note: All devices are specified over the -40°C to +85°C operat-
ing temperature range.
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 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)
Typical Operating Circuit
BATT
2.7V TO 5.5V
2.2μF
PA ON/OFF
ANALOG CONTROL
FORCED BYPASS
LDO1 ON/OFF
LDO2 ON/OFF
BATT
2.7V TO 5.5V
IN1A
PAA
IN1B
PAB
LX
MAX8805Z
PA_EN
PGND
REFBP
REFIN
HP
AGND
EN1
LDO1
EN2
IN2
LDO2
V_PA
0.4V TO V_BATT
1μH
2.2μF
V_LDO1 UP
TO 200mA
V_LDO2 UP
TO 200mA
Pin Configuration appears at end of data sheet.
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