U6432B-FP ATMEL [ATMEL Corporation], U6432B-FP Datasheet - Page 4

• Manufacturer Part Number: U6432B-FP
• Description: Low-power Flasher IC with 18-mOMShunt
• Manufacturer: ATMEL [ATMEL Corporation]

Functional Description
Pin 1, GND
Pin 2, Supply Voltage,
V
Pin 3, Relay Control
Output (Driver)
Pin 4 and 5, Oscillator
Pin 6, Supply Voltage,
Sense
Pin 7
Control Signal Threshold
(49 mV Comparator)
Control Signal Threshold 2
(15-mV Comparator)
4
S
power
U6432B
The U6432B is protected against damage in case of battery reversal via resistor R
ground (-31). An integrated protection circuit together with external resistances R
R
The arrangement of the supply connections to Pin 2 (and 6) must be so as to ensure
that on the connection printed circuit board (PCB), the resistance of V
than that to Pin 2.
The relay control output is a high-side driver with a low saturation voltage. It is capable
of driving a typical automotive relay with a minimum coil resistance of 60 W .
The flashing frequency, f
mula below (see Figure 1):
where C
In case of a lamp outage (see Pin 7) the oscillator frequency is switched to the lamp out-
age frequency f
Duty cycle in normal flashing mode: 50%
Duty cycle in lamp outage mode: 40% (bright phase)
For accurate monitoring via the shunt resistor, a minimized layer resistance from point
V
The detection point for lamp failure can be calculated from the control signal threshold,
typically 49 mV with V
quency change-over is reached at a lamp load of 21 W + 11.4 W. The variation of the
control signal threshold supply voltage takes into account the PTC characteristic of fila-
ment lamps.
A voltage drop at the shunt resistor R
in frequency doubling mode.
If the voltage drop decreases to a value below V
disabled.
This can be achieved either with a switch which by-passes the shunt resistor (e.g., a
special hazard warning switch) or with a small lamp load.
Flasher operation starts with a lamp load of P
f
1
S
4
»
/shunt to Pin 6 is recommended.
limits the current pulses in the IC.
---------------------------------- - Hz
R
1
´
1
C
1
1
£ 47 µF, R
´
1.5
2
with f
1
= 6.8 k W to 510 k W
2
S
» 2.2 ´ f
= 12 V. With a measuring resistance of R
1
, is determined by the R
1
.
3
between 49 mV and 15 mV lets the flasher work
L
³ 1 W.
R3MAX
1
C
1
components as given by the for-
= 15 mV, frequency doubling is
3
= 18 m W , the fre-
S
to Pin 6 is lower
4725A–AUTO–06/03
2
and
4
to