MAX7057ASE+ Maxim Integrated Products, MAX7057ASE+ Datasheet - Page 8

• Manufacturer Part Number: MAX7057ASE+
• Description: RF Transmitter IC TRANSMITTER ASK/FSK
• Manufacturer: Maxim Integrated Products

Specifications of MAX7057ASE+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

300MHz to 450MHz Frequency-Programmable
ASK/FSK Transmitter
The MAX7057 is frequency programmable from 300MHz
to 450MHz, by using a fractional-N phase-locked loop
(PLL), and transmits data using either ASK or FSK mod-
ulation. The MAX7057 has integrated tuning capacitors
at the output of the power amplifier (PA) to ensure high-
power efficiency at various programmable frequencies
with a single-matching network.
The crystal-based architecture of the MAX7057 elimi-
nates many of the common problems with SAW trans-
mitters by providing greater modulation depth, faster
frequency settling, tighter transmit frequency tolerance,
and reduced temperature dependence. In particular,
the tighter transmit frequency tolerance means that a
superheterodyne receiver with a narrower IF bandwidth
(therefore lower noise bandwidth) can be used. The
payoff is better overall receiver performance when using
8
PIN
10
11
12
13
14
15
16
_______________________________________________________________________________________
1
2
3
4
5
6
7
8
9
ENABLE
PAGND
PAOUT
PAVDD
NAME
XTAL2
XTAL1
AGND
DGND
DVDD
ROUT
AVDD
SCLK
GPO
DIN
SDI
CS
Serial Interface Active-Low Chip Select. Internally pulled up to DVDD.
Serial Interface Data Input. Internally pulled down to GND.
Serial Interface Clock Input. Internally pulled down to GND.
Power Amplifier Ground
Power Amplifier Output. Requires a pullup inductor to the supply voltage or ROUT. The pullup inductor can
be part of the output-matching network.
Envelope-Shaping Output. ROUT controls the power amplifier envelope’s rise and fall times. Connect
ROUT to the PA pullup inductor or to an optional power-adjust resistor. Bypass the inductor to GND as
close as possible to the inductor with 680pF and 220pF capacitors.
Power Amplifier Supply Voltage. Bypass to ground with 0.01µF and 220pF capacitors placed as close as
possible to the pin.
Analog Positive Supply Voltage. Bypass to ground with 0.1µF and 0.01µF capacitors placed as close as
possible to the pin.
Crystal Input 2. XTAL2 can be driven from an AC-coupled external reference.
Crystal Input 1. Bypass to ground if XTAL2 is driven from an AC-coupled external reference.
Analog Ground
Enable Pin. Drive high for normal operation; drive low or leave unconnected to put the device in standby
mode. Internally pulled down to GND.
ASK/FSK Data Input. Use the control register (address: 0x00) to select the type of modulation. Internally
pulled down to GND.
Digital Ground
General-Purpose Output. Can be configured to output various digital signals (SPI serial data output—SDO,
CLKOUT—reference oscillator frequency divided by 1, 2, 4, or 8 for microprocessor clock, etc).
Digital positive supply voltage. Bypass to ground with 0.1µF and 0.01µF capacitors placed as close as
possible to the pin.
Detailed Description
a superheterodyne receiver such as the MAX1471,
MAX1473, MAX7033, MAX7034, or MAX7042.
The MAX7057 is a crystal-referenced phased-locked
loop (PLL) VHF/UHF transmitter that transmits data over
the frequency range of 300MHz to 450MHz in ASK or
FSK mode. The transmit frequency is set by the crystal
frequency and the programmable divider in the PLL;
the programmable-divide ratios can be set anywhere
from 19 to 28, which means that with a crystal frequen-
cy of 16MHz, the output frequency range can be from
304MHz to 448MHz.
The fractional-N architecture of the PLL in the MAX7057
allows the FSK signal to be programmed for exact fre-
quency deviations and rapid, transient-free frequency
settling time. This modulation method completely elimi-
FUNCTION
Frequency Programming
Pin Description