u6432b ATMEL Corporation, u6432b Datasheet - Page 5

• Manufacturer Part Number: u6432b
• Description: Low-power Flasher Ic With 18-m? Shunt U6432b
• Manufacturer: ATMEL Corporation

4.6.2
4.7
5. Application Hint
4725C–AUTO–10/06
Pin 8, Start Input
Control Signal Threshold 2 (15-mV Comparator)
A voltage drop at the shunt resistor R
quency doubling mode.
If the voltage drop decreases to a value below V
This can be achieved either with a switch which bypasses the shunt resistor (for example, a spe-
cial hazard warning switch) or with a small lamp load.
Flasher operation starts with a lamp load of P
Start condition for flashing:
Condition for standby:
In order to achieve a high-level immunity against “electrical interference by conduction and cou-
pling” according to ISO/TR 7637/1 test level 4, an electrolytic capacitor C
between pin 1 and 2 – mounted close to the IC – is highly recommended.
• Voltage at pin 8 (see
• V
The resistor R
The leakage current depends on the pull-up resistor R
I
Leak
8
V
S
– (V
(V
BE(T1)
BE(T1)
2
between V
+ V
+ V
Z(D2)
Z(D2)
Figure 2-1 on page
) / R
)
S
2
and pin 8 provides an extremely low standby current (I
3
between 49 mV and 15 mV lets the flasher work in fre-
2)
L
R3MAX
1W.
= 15 mV, frequency doubling is disabled.
2
according to the following formula:
2
= 10 µF (25V)
U6432B
S
10 µA).
5