January, 2000
PRELIMINARY DATASHEET
The ML2721 can be used as a single chip digital cordless
telephone transceiver or general purpose Frequency Shift
Keying (FSK) radio transceiver. It is designed to work in
the 902 to 928MHz ISM band under FCC Part 15
regulations. The device integrates all the frequency
generation, receive and transmit functions for data rates
up to 1.5Mbps. A complete radio only requires the
addition of an antenna switch. Micro Linear's ML2751 is
an integrated 100mW power amplifier and receive LNA
with transmit/receive PIN diode drivers, and it can be
used with the ML2721 for extended range capability.
The ML2721 contains a proprietary low IF receiver with
all channel selectivity. An image reject mixer brings the
915MHz RF signal down to a low IF frequency of
1.024MHz. Then all IF filtering, IF gain, and
demodulation is performed at 1.024MHz. This provides all
the benefits of direct conversion to baseband and
minimizes the need for RF filtering. Also, the ML2721 can
operate with either a low cost LC filter or a SAW filter.
A single 1.83GHz synthesizer is used for both the receiver
LO and the transmitter. The ML2721 transmitter modulates
the VCO with filtered data, and a driver amplifier
provides typically 0dBm at 915MHz. The VCO and PLL
incorporate the resonator, the active devices, and the
tuning circuitry for a completely integrated function. An
internal post detection filter and data slicer are also
included.
The ML2721 contains its own DC regulation which allows
the IC to operate over a wide power supply voltage range.
It also has a simple baseband interface for transmit power
management, PLL control and detection, and RSSI
(Receiver Signal Strength Indication).
n Single chip 900MHz Radio Transceiver
n Fully integrated filters for all IF, FM discriminator and
data filtering
n Image reject mixer & proprietary Low IF architecture
reduce the need for RF filtering
n Integrated 1.83GHz frequency synthesizer with internal
VCO resonator
n TX/RX calibration for max power transmission
n Modulation compensation for improved sensitivity
performance
n PLL Programmed via 3-wire interface
n DC regulation for 2.7V to 5.0V operation (IC
performance is reduced from 2.7V to 3.2V)
n PLL lock detect output
n Analog Received Signal Strength Indication (RSSI)
output to baseband IC
n Easily upgradable for extended range with ML2751
GENERAL DESCRIPTION
ML2721 Low IF Digital Cordless Transceiver
FEATURES
APPLICATIONS
n 900MHz DSSS cordless phones
n 900 to 930MHz radio transceivers with ranges from 10
feet to 1000 feet and data rates to 1.5Mbps
n Single IC 900MHz low power radio
n FCC Part 15 compliant radio links
n Portable computer/PDA
n TDD and TDMA radios
PRELIMINARY
ML2721
2
January, 2000
PRELIMINARY DATASHEET
PRELIMINARY
TABLE OF CONTENTS
Micro Linear makes no representations or warranties with respect to the accuracy, utility, or completeness of the contents
of this publication and reserves the right to make changes to specifications and product descriptions at any time without
notice. No license, express or implied, by estoppel or otherwise, to any patents or other intellectual property rights is
granted by this document. The circuits contained in this document are offered as possible applications only. Particular uses
or applications may invalidate some of the specifications and/or product descriptions contained herein. The customer is
urged to perform its own engineering review before deciding on a particular application. Micro Linear assumes no liability
whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of Micro Linear products including
liability or warranties relating to merchantability, fitness for a particular purpose, or infringement of any intellectual property
right. Micro Linear products are not designed for use in medical, life saving, or life sustaining applications.
Micro Linear 2000. is a registered trademark of Micro Linear Corporation. All other trademarks are the property of their
respective owners.
Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116;
5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376;
5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174;
5,767,653; 5,777,514; 5,793,168; 5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669; 5,825,165; 5,825,223;
5,838,723; 5.844,378; 5,844,941. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending.
General Description ................................................................................................................................................... 1
Features ...................................................................................................................................................................... 1
Applications ............................................................................................................................................................... 1
Simplified Block Diagrams ......................................................................................................................................... 3
Block Diagram ........................................................................................................................................................... 4
Pin Configuration ....................................................................................................................................................... 5
Pin Descriptions ......................................................................................................................................................... 5
Functional Description ............................................................................................................................................... 8
Introduction .............................................................................................................................................................. 8
Circuit Block Descriptions ........................................................................................................................................ 8
Modes Of Operation .................................................................................................................................................. 10
Overview ................................................................................................................................................................. 10
Receive Modes ........................................................................................................................................................ 10
Transmit Mode ......................................................................................................................................................... 12
Standby Mode .......................................................................................................................................................... 15
Test Mode ................................................................................................................................................................ 15
Control Interfaces ....................................................................................................................................................... 16
Register Information ................................................................................................................................................. 17
Transmit and Receive Data Interfaces ...................................................................................................................... 22
Applications ............................................................................................................................................................... 23
Electrical Characteristics ............................................................................................................................................ 24
Electrical Tables ......................................................................................................................................................... 24
Absolute Maximum Ratings ........................................................................................................................................ 24
Operating Conditions ................................................................................................................................................. 24
Physical Dimensions .................................................................................................................................................. 28
Ordering Information .................................................................................................................................................. 28
WARRANTY
ML2721
5
January, 2000
PRELIMINARY DATASHEET
PRELIMINARY
PIN DESCRIPTIONS
PIN CONFIGURATION
Power & Ground
13
VCC
2
I (analog)
DC Power Supply Input to the VCO voltage regulator
24
VCC
5
I (analog)
DC power supply Input to Voltage Regulators and unregulated loads:
2.7 to 5.0V. VCC
5
is the main (or master) analog VCC pin. There must
be a capacitor to ground from this pin to decouple (bypass) noise and
to stabilize the regulator
16
GND
I (analog)
DC ground for VCO and LO circuits
10
RVCC
1
O (analog)
DC power supply decoupling point for the PLL dividers, phase detector,
and charge pump. This pin is connected to the output of the regulator
and to the PLL supplies. There must be a capacitor to ground from this
pin to decouple (bypass) noise and to stabilize the regulator
14
RVCC
3
O (analog)
DC power supply decoupling point for the VCO. Connected to the
output of the VCO regulator. There must be a capacitor to ground from
this pin to decouple (bypass) noise and to stabilize the regulator
22
RVCC
4
O (analog)
DC power supply decoupling point for the LO Chain. Connected to the
output of a regulator. There must be a capacitor to ground from this pin
to decouple (bypass) noise and to stabilize the regulator
27
RVCC
6
O (analog)
DC power supply decoupling point for Quadrature Mixer and IF filter
circuits. There must be a capacitor to ground from this pin to decouple
(bypass) noise and to stabilize the regulator
Pin #
Signal Name
I/O
Description
VCC
5
TRFO
RVCC
4
RRFI
GND
GND
GND
GND
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
32 31 30 29 28 27 26 25
24
23
22
21
20
19
18
17
XCEN
RXON
PLLEN
EN
DATA
CLK
LD/TPQ
VSS
REF
RVCC
1
QPO
GND
VCC
2
RVCC
3
VTUNE
GND
DOUT
VDD
DIN
RVCC
7
RSSI/TPI
RVCC
6
VBG
GND
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ML2721
32-Pin TQFP (H32-7)
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