Datasheet

L4978
2/13
Table 2. Block Diagram
Figure 3. Pins Connection (Top view)
Table 3. Pin Description
Pin Name Function
1 2 GND Ground
2 3 SS_INH A logic signal (active low) disables the device (sleep mode operation).
A capacitor connected between this pin and ground determines the soft start time.
When this pin is grounded disables the device (driven by open collector/drain).
3 4 OSC An external resistor connected between the unregulated input voltage and this pin
and a capacitor connected from this pin to ground fix the switching frequency. (Line
feed forward is automatically obtained)
INHIBIT SOFTSTART
VOLTAGES
MONITOR
THERMAL
SHUTDOWN
E/A
PWM
3.3V
OSCILLATOR
R
S
Q
INTERNAL
REFERENCE
INTERNAL
SUPPLY
3.3V
5.1V
DRIVE
CBOOT
CHARGE
CBOOT
CHARGE
AT LIGHT
LOADS
2
7
8
FB
COMP
SS_INH
3
1
4
6
5
BOOT
OSC GND OUT
VCC
D97IN594
GND
SS_INH
OSC
OUT
1
3
2
4 VCC
BOOT
COMP
FB8
7
6
5
D97IN595
N.C.
GND
SS_INH
OSC
OUT
N.C.
OUT
N.C. N.C.
N.C.
BOOT
VCC
COMP
FB
N.C.
N.C.1
3
2
4
5
6
7
8
14
13
12
11
10
9
15
16
D97IN596
DIP-8 SO16W