Datasheet

6
Notes on Supply Current
The supply current for the
HSDL-3201 has two different
components, DC and AC.
The DC component is measured in
two states, normal (idle mode) and
shutdown. This current is present
whenever power is applied to the
part.
The AC component is either the extra
current drawn from the V
CC
pin by the
photodiode when it sees light, or the
current needed by the LED current
circuit. The values in the table are peak
values. Since IrDA data is transmitted
with a 3/16 duty cycle, the average
value is 3/16 of the peak. The AC
current is not drawn when no light is
present.
Notes:
1. C1 must be placed within 0.7 cm of the HSDL-3201 to obtain optimum noise immunity.
2. If TXD is stuck in the high state, the LED will turn off after about 20 μs.
3. RXD will echo the TXD signal while TXD is transmitting data.
4. In-Band IrDA signals and data rates 115.2 Kb/s.
5. RXD Logic Low is a pulsed response. The pulse width is 2.4 μs, independent of data rate.
6. RXD Logic High during shutdown is a weak pullup resistor (300 kΩ).
7. An in-band optical signal is a pulse/sequence where the peak wavelength, lp, is defined as 850 nm lp 900 nm, and the pulse characteristics
are compliant with the IrDA Serial Infrared Physical Layer Link Specification.
8. For in band signals 115.2 Kb/s where 8.1 μW/cm
2
EI 500 mW/cm
2
.
9. Latency is defined as the time from the last TXD light output pulse until the receiver has recovered full sensitivity.
10. Receiver wake up time is measured from the SD pin high to low transition or V
CC
power on, to a valid RXD output.
11. Transmitter wake up time is measured from the SD pin high to low transition or V
CC
power on, to a valid light output in response to a TXD pulse.
12. Typical values are at EI = 10 mW/cm
2
13. Maximum value is at EI = 500 mW/cm
2
.
14. Current is due to internal stages of the LED current mirror. This current is in addition to the ILED current.
Figure 1. LED current vs. V
CC
. Figure 2. LED current vs. VLED.
ILED – mA
34.0
V
CC
– VOLTS
32.5
3.1 3.4
31.0
31.5
2.7 3.6
33.0
2.8 3.2
33.5
32.0
2.9 3.0 3.3 3.5
VLED = 3.6 VOLTS
ILED – mA
34.0
VLED – VOLTS
32.5
3.1 3.4
31.0
31.5
2.7 3.6
33.0
2.8 3.2
33.5
32.0
2.9 3.0 3.3 3.5
V
CC
= 3.6 VOLTS
V
CC
= 3.3 VOLTS
V
CC
= 3.0 VOLTS
V
CC
= 2.7 VOLTS
Distances between Units to
See a 10 mW/cm
2
Light
Level
Type of
Transceiver Distance (cm)
Typical HSDL-3201 1.0
Max. Brightness 1.7
HSDL-3201
Typical SIR 2.0
Typical FIR 3.2
The 500 mW/cm
2
light level is for the
maximum brightness IrDA unit at 1
cm.
Figure 1. LED current vs. VCC. Figure 2. LED current vs. VLED.