LT8900 Datasheet Revision 1.2
LT8900
Low Cost 2.4GHz Radio Transceiver
FEATURES
Complete 2.4 GHz radio transceiver includes
fully integrated RF PLL and channel filtering
Supports
Frequency-Hopping
Spread
Spectrum
Supports SPI and I2C bus interface
Built-in smart auto-acknowledge Tx/Rx
protocol simplifies usage
Packet data rate 1 Mbps over-the-air
FIFO flag signal permits continuous streaming
data at 1 Mbps over-the-air
Power management for minimizing current
consumption
Digital readout of RSSI and temperature
Lead-free 4x4mm QFN Package & SOP16
for best RF performance
GENERAL DESCRIPTION
The
LT8900
is
a
low-cost,
fully
integrated
CMOS
RF transceiver, GFSK data
modem, and packet framer, optimized for use in the 2.4
GHz ISM band. It contains transmit, receive, RF
synthesizer, and digital modem functions, with few
external components. The transmitter supports digital
power control. The receiver utilizes extensive digital
processing for excellent overall performance, even in
the presence of interference and transmitter
impairments.
The LT8900 transmits GFSK data at approximately 1
dBm output power. The low-IF receiver architecture
produces good selectivity, with sensitivity down to
approx. -87 dBm. Digital RSSI values are available to
monitor channel quality.
On-chip transmit and receive FIFO registers are
available to buffer the data transfer with MCU.
Over-the-air data rate is always 1 Mbps even
when connected to a slow, low-cost MCU.
Built-in CRC, FEC, data whitening, and automatic
retry/acknowledge are all available to simplify and
optimize performance for individual applications.
The digital baseband interface can be either 4-wire SPI
or 2-wire I2C-bus. Three additional pins are available
for optional reset and buffer control.
For extended battery life, power consumption is
minimized all key areas. A sleep mode is available to
reduce standby current consumption to just 1 uA
typ. while preserving register settings.
This product is available in RoHS compliant 24-lead
4x4 mm JEDEC standard QFN package, featuring an
exposed pad on the bottom for best RF characteristics.
Also available in bare die form.
Application
Remote controls
Wireless keyboards and mice
Proprietary Wireless Networks
Home automation
Commercial and industrial short-range
wireless
Wireless voice, VoIP, Cordless headsets
Robotics and machine connectivity
LT8900 Datasheet Revision 1.2
1. Block Diagram
Page 2
December
2010
LT8900 Datasheet Revision 1.2
2. Absolute Maximum Ratings
Table 1. Absolute Maximum Rating
Parameter
Operating Temp.
Storage Temp.
LDO_VDD, VDD_IO Voltage
VDD pins
Applied Voltages to
V
OTHER
Other Pins
Input RF Level
Output Load mismatch (Z0=50Ω)
P
IN
VSWROUT
+10
10:1
dBm
VSWR
-0.3
+3.7
VDC
Symbol
T
OP
T
STORAGE
V
IN_MAX
VDD_MAX
MIN
-40
-55
TYP
MAX
+85
+125
+3.7
+2.5
Unit
ºC
ºC
VDC
Notes:
1.
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Recommended operating conditions
indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For
guaranteed specifications and test conditions, see the Electrical Characteristics section below.
2.
These devices are electro-static sensitive. Devices should be transported and stored in anti-static containers. Equipment and
personnel contacting the devices need to be properly grounded. Cover workbenches with grounded conductive mats.
Page 3
December
2010
LT8900 Datasheet Revision 1.2
3. Electrical Characteristics
Table 2. Electrical Characteristics
The following specifications are guaranteed for TA = 25 C, LDO_VDD= VDD_IO = 3.3 VDC, unless otherwise noted.
Parameter
Supply Voltage
DC power supply voltage range
Current Consumption
Current Consumption - TX
Current Consumption - RX
Current Consumption –IDLE
Current Consumption - SLEEP
Digital Inputs
0.8
Logic input high
Logic input low
Input Capacitance
Input Leakage Current
Digital Outputs
0.8
Logic output high
Logic output low
Output Capacitance
Output Leakage Current
Rise/Fall Time (SPI)
Clock Signals
CLK rise, fall time (SPI)
CLK frequency range (SPI)
Overall Transceiver
Operating Frequency Range
Antenna port mismatch
(Z0=50Ω)
F_OP
VSWR_I
VSWR_O
2400
<2:1
<2:1
2482
MHz
VSWR
VSWR
Receive mode.
Transmit mode.
Tr_spi
FSPI
0
12
25
nS
MHz
Requirement for error-free register
reading, writing.
VOH
VDD_IN
VOL
C_OUT
I_LEAK_OUT
T_RISE_OUT
0.4
10
10
5
V
pF
uA
nS
VDD_IN
V
VIH
VDD_IN
VIL
C_IN
I_LEAK_IN
0
VDD_IN
0.8
10
10
V
pF
uA
1.2
V
IDD_TXH
IDD_TXL
IDD_RX
IDD_IDLE1
IDD_IDLE2
IDD_SLP
18
12
17
1.4
1.1
1
mA
mA
mA
mA
mA
uA
Configured
running.
for
BRCLK
output
POUT = high power setting
POUT = low power setting
1.9
3.6
VDC`
Input to VDD_IO and LDO_VDD
pins.
Symbol
MIN
TYP
MAX
Units
Test Condition and Notes
Configured for BRCLK output OFF.
Page 4
December
2010
LT8900 Datasheet Revision 1.2
Parameter
Receive Section
Receiver sensitivity
Maximum useable signal
Data (Symbol) rate
Min. Carrier/Interference ratio
Co-Channel Interference
Adjacent Ch. Interference,
Symbol
MIN
TYP
MAX
Unis
Test Condition and Notes
Measured using 50 Ohm balun. For
BER
≤
0.1%:
-87
-20
Ts
1
1
dBm
dBm
us
FEC off.
For BER
≤
0.1%
CI_cochannel
CI_1
+9
+6
dB
dB
-60 dBm desired signal.
-60 dBm desired signal.
1MHz offset
Adjacent Ch. Interference,
CI_2
2MHz offset
Adjacent Ch. Interference,
CI_3
3MHz offset
OBB_1
Out-of-Band Blocking
For additional test conditions, see
footnote1.
OBB_2
OBB_3
OBB_4
Transmit Section
PAV
RF Output Power
-17
Second harmonic
Third harmonic
Modulation Characteristics
Peak
FM
Deviation
00001111 pattern
01010101 pattern
∆f1avg
∆f2max
280
225
kHz
kHz
-50
-50
dBm
dBm
2
6
dBm
-10
-27
-27
-10
dBm
dBm
dBm
dBm
30 MHz
2000 MHz
2000 MHz
2400 MHz
2500 MHz
3000 MHz
3000 MHz
12.75 GHz
to
to
to
to
Desired
sig.
-67
dBm, BER
≤
0.1%.
Meas. with ACX
BF2520 ceramic filter
2 on ant. pin .
-24
dB
-67 dBm desired signal.
-12
dB
-60 dBm desired signal.
Measured using 50 Ohm balun3:
POUT=
maximum
Reg09=0x4000
POUT = nominal
Reg09=0x1840
POUT=minimum
power,Reg09=1FC0
Conducted to ANT pin.
Conducted to ANT pin.
output
output
power
power,
output
In-Band Spurious Emission
2MHz offset
>3MHz offset
Out-of-Band Spurious
Emission, Operation
Note:
1.
The test is run at one midband frequency, typically 2460 MHz. With blocking frequency swept in 1 MHz steps, up to 24 exception
frequencies are allowed. Of these, no more than 5 shall persist with blocking signal reduced to -50dBm. For blocking
frequencies below desired receive frequency, in-band harmonics of the out-of-band blocking signal are the most frequent cause
of failure, so be sure blocking signal has adequate harmonic filtering.
In some applications, this filter may be incorporated into the antenna, or be approximated by the effective antenna bandwidth.
Transmit power measurement is corrected for insertion loss of Balun, in order to indicate the transmit power at the IC pins.
IBS_2
IBS_3
OBS_O_1
OBS_O_2
OBS_O_3
OBS_O_4
< -60
-45
< -60
< -65
-40
-60
-36
-30
-47
-47
dBm
dBm
dBm
dBm
dBm
dBm
30 MHz ~ 1 GHz
1 GHz ~ 12.75 GHz, excludes desired
signal and harmonics.
1.8 GHz ~ 1.9 GHz
5.15 GHz ~ 5.3 GHz
2.
3.
Page 5
December
2010
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