CS3341_09 Datasheet, PDF (6/8 Pages) ON Semiconductor – Alternator Voltage Regulator Darlington Driver

CS3341, CS3351, CS387
REGULATION WAVEFORMS
The CS3341/3351/387 utilizes proportion control to
maintain regulation. Waveforms depicting operation are
shown in Figures 4, 5 and 6, where V_BAT/N is the divided
down voltage present on the Sense pin using R1 and R2
(Figure 7). A sawtooth waveform is generated internally.
The amplitude of this waveform is listed in the electric
parameter section as proportion control. The oscillator
voltage is summed with V_BAT/N, and compared with the
internal voltage regulator (V_REG) in the regulation
comparator which controls the field through the output
“Device Driver.”
Figure 4 shows typical steady−state operation. A 50%
duty cycle is maintained.
Figure 5 shows the effect of a drop in voltage on (V_BAT/N
+ V_OSC). Notice the duty cycle increase to the field drive.
Figure 6 shows the effect of an increase in voltage (above
the regulation voltage) on (V_BAT/N + V_OSC). Notice the
decrease in field drive.
V_BAT/N + V_OSC
V_REG
V_BAT/N + V_OSC
V_REG
V_BAT/N + V_OSC
V_REG
ÎÎÎÎ
Field Driver On
Figure 4. 50% Duty Cycle,
Steady State
ÎÎÎÎ
Field Driver On
Figure 5. > 50% Duty Cycle,
Increased Load
ÎÎÎÎ
Field Driver On
Figure 6. < 50% Duty Cycle,
Decreased Load
STATOR
RECTIFIER
MR2502
MR2502
S
C3
0.047 mF
*C2
10 mF
R1
100 kW
R2
50 kW
C4
0.022 mF
R3 250 W
C1
0.1 mF
R4
18 kW
V_CC
Sense
OSC
STATORSC
Driver
IGN
R6
20 kW
LAMP GND
R5 10 kW
D1
MR2502
2N6284
Power
Darlington
POWER GROUND
R7 10 W
R9
2.4 kW
MPSA13
or CS299
*Note: C2 optional for reduced jitter.
A
F
FIELD
I
Lamp Indicator
R10
510 W
IGNITION
SWITCH
BATTERY
Figure 7. Typical Application DIagram
http://onsemi.com
6