Rainbow Electronics MAX8805Z - Manual

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 60m
Ω 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 (60m
Ω 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
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
60m Ω 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)
MAX8805Y/MAX8805Z
600mA PWM Step-Down Converters in
2mm x 2mm WLP for WCDMA PA Power
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
IN1A
LX
PAA
1 μH
BATT
2.7V TO 5.5V
AGND
PA_EN
REFIN
EN1
EN2
IN2
BATT
2.7V TO 5.5V
PA ON/OFF
ANALOG CONTROL
V
PA
0.4V TO V
BATT
REFBP
IN1B
LDO1 ON/OFF
LDO2 ON/OFF
PAB
LDO2
LDO1
V LDO2 UP
TO 200mA
PGND
HP FORCED BYPASS
2.2 μF
2.2 μF
MAX8805Z
V LDO1 UP
TO 200mA
Typical Operating Circuit
19-0777; Rev 0; 4/07
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.
+ 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.
Pin Configuration appears at end of data sheet.
PART
PIN-
PACKAGE PKG
CODE
SWI T C H I N G
F R EQ U EN C Y
( M H z)
MAX8805YEWExy+T* 16 WLP-16 W162B2+ 1 2
MAX8805ZEWExy+T* 16 WLP-16 W162B2+ 1 4