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, which is optional, 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, λp, is defined as 850 nm ≤ λp ≤ 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.
Distances between Units
to See a 10 mW/cm
2
Light
Level
Type of Distance
Transceiver (cm)
Typical 1.0
HSDL-3201
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 3. Power Supply Ripple
Rejection. (No C1).
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
V
CC
RIPPLE VOLTAGE – V
RIPPLE FREQUENCY – Hz
0.6
0
0.2
10 e+3 10 e+6
0.8
1.0
0.4
100 e+3 1 e+6