631
Communication ICs
IrDA infrared communication IC
(SIR compatible)
RPM-801CB Series
The RPM-801CB Series is an infrared communication IC that is compatible with the IrDA (1.0). The infrared LED, PIN
photodiode and modulator / demodulator circuit have been combined on to a single package. LED current can be con-
trolled using external resistor , and an internal register is provided for setting the baud rate and pulse width of the trans-
mitted light. Connection to a UART requires just three lines (transmit, receive, and control) and a clock.
Applications
Cellular telephones, pagers, PDA, PHS, notebook PCs, and printers.
Features
1) Low power consumption.
2) Infrared emitting, receiver , and modulator / demodu-
lator on the chip.
3) Compatible with the IrDA (1.0).
4) Built-in powerdown mode.
5) Power supply voltage input range 2.7V to 5.5V.
6) External clock input.
7) Light emitting pulse width can be varied.
Block diagram
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Communication ICs RPM-801CB Series
FPin descriptions
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions (Ta = 25_C)
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Communication ICs RPM-801CB Series
Input / output circuits
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Communication ICs RPM-801CB Series
FElectrical characteristics (unless otherwise noted, Ta = 25_C, VDD = 3V)
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Communication ICs RPM-801CB Series
Circuit operation
(1) IrDA format
(2) Register function
Control character format
As shown in the Fig.2, the control character is made up of four address bits, four data bits, a start bit and a stop bit.
(3) Explanation of the registers
Register table
LOAD 0 Do not load the clock divider register value
LOAD 1 Load the clock divider register value
∗ The LOAD bit automatically becomes 0 after the
* clock divider register value is loaded.
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Communication ICs RPM-801CB Series
1) Control register 1
ECHO0 No control character echo back
ECHO1 Control character echo back
ECAN 0 Reception of transmitted (self emitted) data not
cancelled
ECAN 1 Reception of transmitted (self emitted) data
cancelled
RXEN 0 Receiver off
RXEN 1 Receiver on
TXEN 0 Transmitter off
TXEN 1 Transmitter on
2) Control register 2
3) Clock divider register value 1
4) Clock divider register value 2
Baud rate = M input clock frequency / 8
M = (DIV4 select value) (DIV3,2 select value) (DIV1,0 select value)
∗ At reset, the value is set to 1 / 2.
The reset baud rate is therefore: 1 / 2 input clock frequency / 8.
5) Output pulse width register 1
Fig.3
Fig.4
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Communication ICs RPM-801CB Series
6) Output pulse width register 2
Output pulse width = N input clock period / 2
N = (PW4 value) (PW3,2 value) (PW1,0 value)
Note) N x 4/M
M = (DIV4 multiplier) (DIV3,2 multiplier) (DIV1,0 multiplier)
(4) Timing chart
(1) Reset operation
(2) Register write
Fig.5
Fig.6
Fig.7
Fig.8
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Communication ICs RPM-801CB Series
(3) Echo back
(4) Transmit
(5) Receive
(6) Echo cancel
Fig.9
∗ T1 is 1 / baud rate.
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Communication ICs RPM-801CB Series
(7) Power down
Application example
Operation notes
After the power is applied or after a reset via RESET, the
baud rate generator is set to Clock / 16, so perform the
control register setting operation at a communication rate
of Clock / 16.
T o perform infrared communication after the power is ap-
plied or after a reset via RESET, first set the value 3 into
control register 1 (both receiver and transmitter on).
Determine the clock frequency according to the content
of the clock divider registers 1 and 2.
Set the pulse width in accordance with IrDA specifica-
tions.
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Communication ICs RPM-801CB Series
Electrical characteristics curves
External dimensions (Unit: mm)
