HSDL-1100 Agilent(Hewlett-Packard), HSDL-1100 Datasheet - Page 2

• Manufacturer Part Number: HSDL-1100
• Description: General Application Guide for the HSDL-1100 4 Mb/s Infrared Transceiver
• Manufacturer: Agilent(Hewlett-Packard)

HSDL-1100 Functional
Description
Transmitter
The transmitter uses a high speed,
high efficiency TS AlGaAs LED to
produce an Ir signal of intensity
and speed required by IrDA. The
LED drive transistor is Schottky
clamped to aid in meeting the IrDA
optical rise time, and pulse width
specifications. The external
components CX2 and R1 are
recommended to obtain current
peaking, which creates faster
optical pulse edges. Fast optical
edges will help the link meet the
required IrDA power budget.
LED current is set by selection of
RLED. See the Transmitter Drive
Requirements section.
Receiver
The receiver consists of two
channels, Rxd-A (2.4-115.2 kb/s)
and Rxd-B (0.5-4 Mb/s). Both
channels use the same detector
and pre-amplifier stage. Both
channels use CX1, CX5, CX6, and
Table 1.
• The HSDL-1100 transmitter is
Worst Case Immunity
Power Supply Noise Immunity with no external
V
Power Supply Noise Immunity with
recommended V
TV Remote signals correctly.
However, the sensitivity will
allow only 2-3 meters of
transmit to receive distance
unless the transmit power of
the remote signal is
>100 mW/sr.
capable of correct Sharp ASK/
DASK and TV Remote data
transmission at IrDA levels for
transmitted intensity (mW/sr).
CC
filter or decoupling
CC
filter including Cx5, R3, Cx6
R3 to filter out power supply noise.
The Rxd-B channel uses an
adaptive threshold circuit to
minimize pulse width distortion
(PWD) over the IrDA required
dynamic range. The Rxd-B
channel also uses a squelch circuit
to eliminate noise bits on Rxd
when no Ir signal is present. The
adaptive threshold circuit makes
use of CX3 and CX4.
In general, 2.4-115.2 kb/s Ir signals
create output pulses on Rxd-A, and
0.5-4 Mb/s Ir signals create output
pulses on Rxd-B. However, Ir
signals in the 10 kHz - 1 MHz range
may appear on both Rxd-A and
Rxd-B, depending on the Ir signal
strength. The presense of signal at
both Rxd-A and Rxd-B should not
be a problem for any properly
designed I/O chip. The I/O chip
should be designed to look at only
one channel at a time, depending
upon which data mode has been
selected by the software.
Dynamic Range
The dynamic range required by
IrDA for a 1 meter link is 4 W/cm
500 mW/cm
10 W/cm
Mb/s. The wide dynamic range
requires a special circuit which
adjusts to the signal level for
comparison to a threshold. The
adaptive threshold circuit quickly
adjusts to the incoming signal level
and eliminates the need for any
external AGC circuitry or adjust-
ment.
2
-500 mW/cm
2
for 2.4-115.2 kb/s, and
HSDL-1000
2
for 0.5-4
20 mV
Rxd
2
> 1 volt pk-pk
Power Supply Noise Immunity
The HSDL-1100 receiver circuitry is
specially designed for power
supply noise immunity. The result
of the receiver design is improved
power supply noise immunity over
that of the HSDL-1000. Table 1
describes the HSDL-1100 noise
immunity as compared to that of
the HSDL-1000.
the maximum amount of ripple or
noise on V
tolerate without generating any bit
errors. Noise levels above the noise
immunity will effectively reduce
the receiver sensitivity and there-
fore the Ir link distance. Without
any infrared signal present, noise
levels above the noise immunity
could generate pulses on RxdA or
RxdB. The worst case immunity is
defined as the lowest level of noise
immunity in any frequency range.
Ambient Light
The HSDL-1100 receiver design
allows for the ambient light levels
of sunlight, flourescent light, and
incandescent light specified in the
IrDA Physical Layer Specification.
As with the HSDL-1000, several
technologies are used in the HSDL-
1100 design to reduce the effects of
interfering ambient light. The
package mold compound is tinted
with dye to filter out light wave-
lengths below the Ir wavelengths of
850-900 nm. The lens of the detec-
tor is designed to focus light within
the IrDA viewing angle. The pre-
Power Supply Noise immunity is
Rxd-A
90 mV
HSDL-1100
CC
that the receiver can
> 1 volt pk-pk
Rxd-B
70 mV