TI CONFIDENTIAL
TRF7900A
www.ti.com
SWRS031A – OCTOBER 2005 – REVISED DECEMBER 2005
Fully Integrated Analog Front-End Dual Receiver Base
Unit for 27-MHz Wireless Mouse and Keyboard Systems
FEATURES
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23 Discrete Components Intgrated Into One
Chip
– Only External Components are Bypass and
Filter Capacitors, and One Crystal
RF Tuner, Mixer, Transistors, Passives, Coils,
and SAW Filter Functionality All on One Chip
Integrated Phase Locked Loop
8 User-Selectable Frequencies
– Each Channel (Mouse and Keyboard) Can
Independently Select Any of the Available
Frequencies
Internally Generated 6-MHz Clock to Drive
USB Microcontroller
High Data Throughput Rate
– 5-kHz Square Wave Simultaneously per
Channel
– 10 kbps Miller Encoded Data
I2C Control Interface
Received Signal Strength Indicator (4-BIt)
5-V, 52 mA Supply
Available in 28-Pin TSSOP (PW) Package
APPLICATIONS
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27-MHz Wireless Mouse and Keyboard
Systems
Human Interface Devices
Wireless Control
Remote Control Toys
Wireless Headset
Remote instrumentation
DESCRIPTION
The TRF7900A is a dual integrated RF transceiver
designed for Human Interface Devices (HID).
Operating at 27 MHz, it integrates multiple
components (PLL, RF mixer, simulated SAW filter,
tuning
circuit,
and
miscellaneous
passive
components) to provide frequency selection from 8
discrete channels. This integration lowers component,
manufacturing and system costs.
The TRF7900A simplifies system design by reducing
system component count and manual circuit tuning.
By integrating the PLL, SAW filter, and RF mixer, the
TRF7900A eliminates the manual tuning of RLC
circuits required in traditional implementations.
The receiver also generates 8 frequencies that can
be programmatically selected via the I2C interface
bus for both the mouse channel and/or the keyboard
channel. Another 6-MHz clock is internally generated
to clock the USB microcontroller; this enables a
single crystal to be used to supply the clock needs for
the receiver channels and the microcontroller.
The optimized receiver design enables simultaneous
reception on both parallel channels up to 5 kHz (10
kbps Miller encoding) per channel. A receive strength
signal indicator register can be read via the I2C bus to
determine if the transmit signal is too weak (weak
battery or too far), or if there is too much noise on the
selected channel in the user's area.
USB or PS/2
Power
PCB Loop
Antenna
TPS71533
I2C Control
2 Data Channels
6MHz for uP
TRF7900A
12 MHz
Crystal
MSP430
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2005, Texas Instruments Incorporated
TI CONFIDENTIAL
TRF7900A
www.ti.com
SWRS031A – OCTOBER 2005 – REVISED DECEMBER 2005
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated
circuits be handled with appropriate precautions. Failure to observe proper handling and installation
procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision
integrated circuits may be more susceptible to damage because very small parametric changes could
cause the device not to meet its published specifications.
ORDERING INFORMATION
PACKAGED DEVICES
PACKAGE TYPE
TRF7900APW
TRANSPORT MEDIA, QUANTITY
Rails, 50
TSSOP - 28
TRF7900APWR
Tape and Reel, 2000
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted) (1)
VS– to
VS+
Supply voltage
VI
Input voltage
VID
Differential input voltage
Continuous power dissipation
TJ
5.5
V
±VS± 0.5
V
±2
V
Maximum junction temperature, any condition (2)
150
°C
125
°C
–65 to 150
°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds
300
°C
ESD ratings: Human Body Model
4000
V
ESD ratings: Charged Device Model
1500
V
ESD ratings: Machine Model
200
V
Maximum junction temperature, continuous operation, long term
Tstg
Storage temperature range
(2)
UNIT
See Dissipation Rating Table
TJ
(1)
VALUE
reliability (2)
The absolute maximum ratings under any condition is limited by the constraints of the silicon process. Stresses above these ratings may
cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied.
The maximum junction temperature for continuous operation is limited by package constraints. Operation above this temperature may
result in reduced reliability and/or lifetime of the device.
DISSIPATION RATINGS
(1)
(2)
PACKAGE
θJC
θJA (1)
PW (28)
13.7
56.5
POWER RATING (2)
TA≤ 25°C
TA = 85°C
1.77 W
708 mW
This data was taken using the JEDEC standard high-K test PCB.
Power rating is determined with a junction temperature of 125°C. This is the point where distortion starts to substantially increase.
Thermal management of the final PCB should strive to keep the junction temperature at or below 125°C for best performance and long
term reliability.
RECOMMENDED OPERATING CONDITIONS
over operating free-air temperature range (unless otherwise noted)
MIN
VS– to VS+
2
Suppy voltage, analog
4.0
NOM
MAX
5.5
UNIT
V
TI CONFIDENTIAL
TRF7900A
www.ti.com
SWRS031A – OCTOBER 2005 – REVISED DECEMBER 2005
ELECTRICAL CHARACTERISTICS
VS = 5 V, over operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
50
ppm
RF SPECIFICATIONS (1) (2) (3)
Precision of required external
12-MHz crystal
TA = -40°C to 85°C
Channel spacing
TA = 25°C
Communication spacing
RO
kHz
MHz
27.045
MHz
27.095
MHz
27.145
MHz
27.195
MHz
27.295
MHz
Optional channel
27.245
MHz
Optional channel
26.945
MHz
±120
ppm
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