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

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

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

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)

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

REFBP

IN1B

LDO1 ON/OFF

LDO2 ON/OFF

PAB

LDO2

LDO1

TO 200mA

PGND

HP

FORCED BYPASS

2.2

μF

2.2

μF

MAX8805Z

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

SWITCHING

FREQUENCY

(MHz)

MAX8805YEWExy+T* 16 WLP-16

W162B2+1

2

MAX8805ZEWExy+T* 16 WLP-16

W162B2+1

4