E-L4971 Datasheet, PDF (2/13 Pages) STMicroelectronics – 1.5A STEP DOWN SWITCHING REGULATOR

L4971
Figure 2. Block Diagram
THERMAL
SHUTDOWN
VOLTAGES
MONITOR
2
SS_INH
INHIBIT
7
COMP
8
E/A
FB
3.3V
SOFTSTART
3.3V
INTERNAL
REFERENCE
PWM
R
Q
S
OSCILLATOR
3
OSC
1
GND
VCC
5
INTERNAL
SUPPLY _5.1V
DRIVE
CBOOT
CHARGE
6
BOOT
CBOOT
CHARGE
AT LIGHT
LOADS
4
OUT
D97IN594
Figure 3. Pin Connections
GND
SS_INH
OSC
OUT
1
8
2
7
3
6
4
5
D97IN595
FB
COMP
BOOT
VCC
DIP8
N.C.
GND
SS_INH
OSC
OUT
OUT
N.C.
N.C.
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
D97IN596
SO16
N.C.
N.C.
FB
COMP
BOOT
VCC
N.C.
N.C.
Table 2. Pin Description
DIP SO (*) 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 disabled 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)
4
5, 6
OUT Stepdown regulator output
5
11
VCC Unregulated DC input voltage
6
12 BOOT A capacitor connected between this pin and OUT allows to drive the internal DMOS
Transistor
7
13 COMP E/A output to be used for frequency compensation
8
14
FB Stepdown feedback input. Connecting directly to this pin results in an output voltage of
3.3V. An external resistive divider is required for higher output voltages.
(*) Pins 1, 7, 8, 9, 10, 15 and 16 are not internally, electrically connected to the die.
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