switching regulator. L4973 Datasheet

L4973 regulator. Datasheet pdf. Equivalent

L4973 Datasheet
Recommendation L4973 Datasheet
Part L4973
Description 3.5A step down switching regulator
Feature L4973; L4973 3.5 A step down switching regulator Features ■ Up to 3.5 A step down converter ■ Operating .
Manufacture STMicroelectronics
Datasheet
Download L4973 Datasheet




STMicroelectronics L4973
L4973
3.5 A step down switching regulator
Features
Up to 3.5 A step down converter
Operating input voltage from 8 V to 55 V
3.3 V and 5.1 V (±1%) fixed output, and
adjustable outputs from:
– 0.5 V to 50 V (3.3 type)
– 5.1 V to 50 V (5.1 type)
Frequency adjustable up to 300 kHz
Voltage feed forward
Zero load current operation (min. 1 mA)
Internal current limiting (pulse by pulse and
HICCUP mode)
Precise 5.1 V (1.5%) reference voltage
externally available
Input/output synchronization function
Inhibit for zero current consumption (100 mA
typ. at VCC = 24 V)
Protection against feedback disconnection
Thermal shutdown
Output over voltage protection
Soft-start function
Figure 1. Internal schematic diagram
DIP-18 (12+3+3)
SO-20 (12+4+4)
Description
The L4973 is a step down monolithic power
switching regulator delivering 3.5 A at fixed
voltages of 3.3 V or 5.1 V and using a simple
external divider output adjustable voltage up to
50V. Realized in BCD mixed technology, the
device uses an internal power D-MOS transistor
(with a typical RDS(on) of 0.15 Ω) to obtain very
high efficiency and very fast switching times.
Switching frequency up to 300 kHz are achievable
(the maximum power dissipation of the packages
must be observed).
A wide input voltage range between 8 V to 55 V
and output voltages regulated from 3.3 V to 40 V
cover the majority of the today applications.
Features of this new generation of DC-DC
converter includes pulse by pulse current limit,
hiccup mode for output short circuit protection,
voltage feed forward regulation, soft-start,
input/output synchronization, protection against
feedback loop disconnection, inhibit for zero
current consumption and thermal shutdown.
Packages available are in plastic dual in line, DIP-
18 (12+3+3) for standard assembly, and SO20
(12+4+4) for SMD assembly.
VCC (8V to 55V)
ROSC
CIN C2
78
L4973
1
4,5,6,10
13,14,15 16 17
12 CBOOT
9
3
2
11
L1
VO(3.3V or 5.1V)
COSC
CSS
RCOMP
CCOMP
D1
COUT
February 2009
D97IN554A
Rev 18
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www.st.com
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STMicroelectronics L4973
Contents
Contents
L4973
1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Evaluation board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8 Application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
10 Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
11 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
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STMicroelectronics L4973
L4973
1 Block diagram
Block diagram
Figure 2. Block diagram
INH
10(11)
ZERO CURRENT
INHIBIT
VREF
GOOD
17(19)
SS
11(12)
COMP
VFB
5.1V
3.3V
12(13)
+
E/A
-
SOFT
START
THERMAL
SHUTDOWN
-
PWM
+
SYNC
18(20)
OSCILLATOR
Pin x = Powerdip
Pin (x) = S020
1(1)
OSC
5.1V
3.3V
V5.1
16(18)
INTERNAL
REFERENCE
VCC
7(8)
VCC
8(9)
CBOOT
CHARGE
INTERNAL
SUPPLY
5.1V
HICCUP CURRENT
LIMITING
CURRENT
LIMITING
RQ
SQ
BOOT
9(10)
4,5,6,13,14,15
(4,5,6,7,14,15,16,17)
GND
DRIVER
2(2)
OUT
3(3)
OUT
D94IN161B
2
2.1
Pin settings
Pin connection
Figure 3. Pin connection (top view)
OSC
OUT
OUT
GND
GND
GND
VCC
VCC
BOOT
1 18
2 17
3 16
4 15
5 14
6 13
7 12
8 11
9 10
D94IN162A
SYNC
SS
V5.1
GND
GND
GND
VFB
COMP
INH
OSC
OUT
OUT
GND
GND
GND
GND
VCC
VCC
BOOT
DIP -18 (12+3+3)
1 20
2 19
3 18
4 17
5 16
6 15
7 14
8 13
9 12
10 11
D94IN163A
SO20 (12+4+4)
SYNC
SS
V5.1
GND
GND
GND
GND
VFB
COMP
INH
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