Dynamic Range

The dynamic range required by
IrDA for a 1 meter link is 4 W/cm2
500 mW/cm2 for 2.4-115.2 kb/s, and
10 W/cm2-500 mW/cm2 for 0.5-4
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 adjustment.
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.
Power Supply Noise immunity is
the maximum amount of ripple or
noise on VCC that the receiver can
tolerate without generating any bit
errors. Noise levels above the noise
immunity will effectively reduce
the receiver sensitivity and therefore
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.