U2482B
| Model | U2482B |
| Description | Automotive Lamp Outage Monitor |
| PDF file | Total 11 pages (File size: 153K) |
| Chip Manufacturer | ETC |
U2481B/ U2482B
Integrated Delay, Debouncing, Failure Dis-
play
As soon as a comparator detects a failure a slow upward
counter is started in order to generate the delay time,
t
del
= 1.2 s. With a consistent failure the output stage is
enabled after t
del
. If the failure disappears during t
del
a fast
downward counter is started in order to generate the reset
time t
reset
y
135 ms. The upward counter is reset, the
output stage stays disabled.
Benefits: Intermittent contacts in the wire harness do not
activate the pilot lamp! Even cyclical intermittent
contacts are screened out as long as the pulse/pause ratio
is smaller than 10:1. In the case of higher duty cycles the
upward counter may reach its trigger threshold for the
output activation after t > t
del
.
Individual delay- and reset times can be adjusted with
external R/C components according to (see “oscillator”)
– t
del
= 1930 x t
osc
– t
reset
= 198 x t
osc
TELEFUNKEN Semiconductors
Latch for Brake Lamp Monitor
A failure of a brake lamp detected by comparator K7 or
a blown fuse in the brake circuitry is memorized after the
delay time has expired.
A reset of the latch can only be performed with a “power-
on-reset”.
Output Stage
The output is a Darlington stage stage with protection
diodes to V
S
and IC ground. The output is designed to
drive an external pilot lamp with an external PNP
transistor.
At the end of the delay time the output stage is switched
on and can source a current of I
out
= –10 mA with a typical
saturation voltage of V
sat
= 1 V.
Test Mode
With V
TEST
= 23 V (20 mA) applied to Pin osc, via a
200
W
resistor the delay time stage can be bypassed for
test purposes. A failure detection will be displayed
immediately to save time during threshold testing.
6 (11)
Preliminary Information
Rev. A1: 21.08.1995
