General Description

The MAX7057 frequency-programmable UHF transmit-

ter is designed to transmit ASK/FSK data at a wide

range of frequencies from 300MHz to 450MHz. The

MAX7057 has internal tuning capacitors at the output of

the power amplifier that are programmable for match-

ing to an antenna or load. This allows the user to

change to a new frequency and match the antenna at

the new frequency simultaneously. The MAX7057 trans-

mits at a data rate up to 100kbps nonreturn-to-zero

(NRZ) (50kbps Manchester coded). Typical transmitted

power into a 50

Ω load is +9.2dBm with a +2.7V supply.

The device operates from +2.1V to +3.6V and typically

draws under 12.5mA of current in FSK mode (8.5mA in

ASK mode) when the antenna-matching network is

designed to operate over the 315MHz to 433.92MHz

frequency range. For narrower operating frequency

ranges, the matching network can be redesigned to

improve efficiency. The standby current is less than

1µA at room temperature.

The MAX7057 reference frequency from the crystal

oscillator is multiplied by a fully integrated fractional-N

phase-locked loop (PLL). The multiplying factor of the

PLL is set by a 16-bit number, with 4 bits for integer

and 12 bits for fraction; the multiplying factor can be

anywhere between 19 and 28. The 12-bit fraction in the

synthesizer sets a tuning resolution equal to the refer-

ence frequency divided by 4096; frequency deviation

can be set as low as ±2kHz and as high as ±100kHz.

The fractional-N synthesizer eliminates the problems

associated with oscillator-pulling FSK signal generation.

The MAX7057 has a serial peripheral interface (SPI™)

for selecting all the necessary settings.

The MAX7057 is available in a 16-pin SO package and

is specified to operate in the -40°C to +125°C automo-

tive temperature range.

Applications

RF Remote Controls

Garage Door Openers

Home Automation

Automotive

Wireless Sensors

Wireless Game Consoles

Wireless Computer Peripherals

Security Systems

Features

o Programmable Frequency Operation with Single

Crystal

o Internal Variable Capacitor for Antenna Tuning

with Single-Matching Network

o 100kbps Data Rate (NRZ)

o +2.1V to +3.6V Single-Supply Operation

o < 12.5mA (FSK), < 8.5mA (ASK) DC Current Drain

o < 1µA Standby Current

o ASK/FSK Modulation

o 47% Carrier Tuning Range Using One Crystal

300MHz to 450MHz Frequency-Programmable

ASK/FSK Transmitter

________________________________________________________________

Maxim Integrated Products

1

Pin Configuration

Ordering Information

19-4093; Rev 1; 4/11

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

EVALUATION

KIT

AVAILABLE

+

Denotes a lead(Pb)-free package/RoHs-compliant package.

PART

TEMP RANGE

PIN-PACKAGE

MAX7057ASE+

-40°C to +125°C

16 SO

Typical Application Circuit and Functional Diagram appear

at end of data sheet.

SPI is a trademark of Motorola, Inc.

DGND

DIN

PAGND

1

+

2

DVDD

GPO

SDI

SCLK

CS

TOP VIEW

3

4

AGND

XTAL1

XTAL2

PAVDD

AVDD

5

ENABLE

PAOUT

ROUT 6

7

8

MAX7057

14

13

16

15

12

11

10

9