DVD Recorder User Manual

3
Bandwidth Selection Timing
The transceiver is in default SIR/ MIR mode when pow-
ered on. User needs to apply the following program-
ming sequence to both the SD and TXD inputs to en-
able the transceiver to operate at FIR mode.
Setting the transceiver to SIR/MIR Mode (9.6 kbit/s to
1.152 Mbit/s)
1. Set SD/Mode input to logic HIGH
2. TXD input should remain at logic LOW
3. After waiting for t
S
≥ 25 ns, set SD/Mode to logic LOW,
the HIGH to LOW negative edge transition will deter-
mine the receiver bandwidth
4. Ensure that TXD input remains low for t
H
≥ 100 ns, the
receiver is now in SIR/MIR mode
5. SD input pulse width for mode selection should be >
50 ns.
Setting the transceiver to FIR (4.0 Mbit/s) Mode
1. Set SD/Mode input to logic HIGH
2. After SD/Mode input remains HIGH at > 25 ns, set TXD
input to logic HIGH, wait t
S
≥ 25 ns (from 50% of TXD
rising edge till 50% of SD falling edge)
3. Then set SD/Mode to logic LOW, the HIGH to LOW
negative edge transition will determine the receiver
bandwidth
4. After waiting for t
H
≥ 100 ns, set the TXD input to logic
LOW
5. SD input pulse width mode selection should be >
50 ns.
Figure 3. Bandwidth selection timing at SIR/MIR mode. Figure 4. Bandwidth selection timing at FIR mode.
Transceiver I/O Truth Table
Inputs Outputs
TXD Light Input to Receiver SD LED RXD Note
High Don’t Care Low On Not Valid
Low High Low O Low 12,13
Low Low Low O High
Don’t Care Don’t Care High O High
Notes:
12. In-band IrDA signals and data rates ≤ 4.0 Mbit/s
13. RXD logic low is a pulsed response. The condition is maintained for a duration dependent on pattern and
strength of the incident intensity.
CAUTIONS: The BiCMOS inherent to the design of this component increases the component’s susceptibility to
damage from electrostatic discharge (ESD). It is advised that normal static precautions be taken in handling and
assembly of this component to prevent damage and/or degradation which may be induced by ESD.
Figure 3. Bandwidth selection timing at SIR/MIR mode. Figure 4. Bandwidth selection timing at FIR mode.
V
IH
50%
t
S
t
H
V
IL
50%50%TXD
SD/MODE
V
IL
V
IH
50%
t
S
t
H
V
IL
50%50%TXD
SD/MODE
V
IH
V
IL