SM8313
150Khz, 3A PWM Buck Switching Regulator
General Description
The SM8313 series are monolithic integrated
circuits that provide all the active functions for a
step-down DC/DC converter, capable of driving a
3A load without additional transistor component.
Requiring a minimum number of external
component, the board space can be saved easily.
The external shutdown function can be controlled
by TTL logic level and then come into standby
mode. The internal compensation makes feedback
control have good line and load regulation without
external design. Regarding protected function,
thermal shutdown is to prevent over temperature
operating from damage, and current limit is against
over current operating of the output switch. The
SM8313 series operates at a switching frequency of
150Khz thus allowing smaller sized filter
components than what would be needed with lower
frequency switching regulators. Other features
include a guaranteed +4% tolerance on output
voltage under specified input voltage and output
load conditions, and +15% on the oscillator
frequency. The output version included fixed 3.3V,
5V, 12V, and an adjustable type. The packages are
available in a standard 5-lead TO-220(T) package
and a 5-lead TO-263(S).
Features
-
3.3V, 5V, 12V and adjustable output versions
-
Adjustable version output voltage range, 1.23V to
28V +4% max over line and load condiction
-
Available in TO220-5L and TO263-5L packages
-
Voltage mode non-synchronous PWM control
-
Thermal-shutdown and current-limit protection
-
ON/OFF shutdown control input
-
Input voltage range up to 32V
-
Output load current: 3A
-
150 kHz fixed frequency internal oscillator
-
Low power standby mode
-
Built-in switching transistor on chip
Applications
-
Simple High-efficiency step-down(buck) regulator
-
Efficient preregulator for linear regulators
-
On-card switching regulators
-
Positive to negative converter
- Battery Charger
Pin Assignments
( Top View )
5 SD
4 FB
3 Gnd
2 Output
1 V
IN
Pin Descriptions
Name
V
IN
Output
Gnd
FB
Description
Operating voltage input
Switching output
Ground
Output voltage feedback control
ON/OFF Shutdown
Metal Tab GND
TO263-5L
( Top View )
5 SD
4 FB
3 Gnd
2 Output
1 V
IN
TO220-5L
This
SD
this pr
product information. Kalai Techno ogy Corp. reserves the rights to modify the product specification without notice. No liab
o igh
any p
e of the product.
assumed as
result of
1/10
A AI
Rev. 1.0, Oct.10, 2005
TECHNOLOGY CORPORATION
SAMHOP Microelectronics Corp.
150Khz, 3A PWM Buck Switching Regulator
Ordering Information
SM 8313
XX X X
Output version
Blank : Adjustable
-33 : 3.3V
-50 : 5.0V
-12 : 12V
Package
T: TO220-5L
S: TO263-5L
Packing
Blank : Tube
A : Taping
SM8313
Block Diagram
SD
V
IN
200mV
Current
Source
bias
1.235V
Reference
2.5V
Regulator
Start
up
220mV
+
Comp
_
Comp
+
+
FB
_
Comp
+
_
Amp
Pre-driver
150kHz
OSC.
Thermal
Limit
2/10
_
3A
Switch
Output
Gnd
SAMHOP Microelectronics Corp.
150Khz, 3A PWM Buck Switching Regulator
Absolute Maximum Ratings
Symbol
V
CC
V
SD
V
FB
V
OUT
P
D
T
ST
T
OP
V
OP
Parameter
Supply Voltage
ON/OFF Pin input voltage
Feedback Pin voltage
Output voltage to Ground
Power dissipation
Storage temperature
Operating temperature
Operating voltage
SM8313
Rating
+34
-0.3 to +25
-0.3 to +25
-1
Internally limited
-65 to +150
-40 to +125
+4.5 to +25
Unit
V
V
V
V
W
o
o
C
C
V
Unless otherwise specified, V
IN
=12V for 3.3V, 5V, adjustable version and V
IN
=24V for the 12V version. I
LOAD
= 0.3A
Electrical Characteristics (All Output Voltage Versions)
Parameter
Feedback bias current
oscillator frequency
saturation voltage
Max. Duty Cycle(ON)
Min. Duty cycle(OFF)
current limit
Output = 0
Output = 1
Output
leakage
current
I
OUT
=3A
no outside circuit
V
FB
=0V force driver on
V
FB
=0V force driver on
V
FB
=12V force driver off
peak current
no outside circuit
V
FB
=0 force driver on
no outside circuit
V
FB
=12 force driver off
V
IN
=32V
V
FB
=12 force driver off
ON/OFF pin=5V
V
IN
=40V
Low (regulator ON)
High (regulator OFF)
-
2.0
1.3
15
0.02
2.5
3.5
28
23
Conditions
V
FB
=1.3V
(Adjustable version only)
127
110
1.3
100
0
3.6
4.5
Min.
Typ.
40
150
Symbol
I
B
F
OSC
V
SAT
DC
I
CL
I
L
I
Q
I
STBY
V
IL
V
IH
I
H
I
L
JC
Max.
60
100
173
173
1.4
1.5
Unit
nA
Khz
V
%
5.5
6.5
200
A
uA
mA
mA
uA
2
5
150
60
10
250
300
0.6
-
25
5
o
Quiescent Current
Standby Quiescent
Current
ON/OFF pin logic input
threshold voltage
V
ON/OFF pin logic
V
LOGIC
=2.5V (OFF)
input current
ON/OFF pin input current V
LOGIC
=0.5V (ON)
Thermal Resistance
Thermal Resistance
With copper area of
approximately 3 in
2
TO220-5L
TO263-5L
TO220-5L
TO263-5L
Junction to
case
Junction to
ambient
uA
C/W
C/W
JA
o
3/10
150Khz, 3A PWM Buck Switching Regulator
Electrical Characteristics (Continued)
Symbol
V
FB
SM8313
Parameter
Output
Feedback
Efficiency
Conditions
5V < V
IN
< 32V
0.2A < I
LOAD
< 3A
V
OUT
programmed for
3V
V
IN
= 12V, I
LOAD
=3A
5.5V < V
IN
< 32V
0.2A < I
LOAD
< 3A
V
IN
= 12V, I
LOAD
=3A
8V < V
IN
< 32V
0.2A < I
LOAD
< 3A
V
IN
= 12V, I
LOAD
=3A
15V < V
IN
< 32V
0.2A < I
LOAD
< 3A
V
IN
= 15V, I
LOAD
= 3A
Typ.
1.23
73
3.3
73
5
80
12
90
Limit
1.193/1.18
1.267/1.28
Unit
V
V
MIN
V
MAX
%
SM8313-ADJ
SM8313-3.3V
V
OUT
Output voltage
Efficiency
3.168/3.135
3.432/3.465
V
V
MIN
V
MAX
%
V
V
MIN
V
MAX
%
V
V
MIN
V
MAX
%
SM8313-5V
V
OUT
Output voltage
Efficiency
4.8/4.75
5.2/5.25
SM8313-12V
V
OUT
Output voltage
Efficiency
11.52/11.4
12.48/12.6
Specifications with
boldface type
are for full operating temperature range, the other type are for T
J
=25ºC.
4/10
150Khz, 3A PWM Buck Switching Regulator
Typical Performance Characteristics
Typical Performance Characteristics
Normalized Output Voltage
Efficiency
100
EFFICIENCY (%)
SM8313
5.10
OUTPUT VOLTAGE CHANGE
V
IN
=20V, I
LOAD
=3A
Normalized at T
J
=25
o
C
5.05
95
90
85
80
75
3A Load
5.00
5V
4.95
3.3V
4.90
-50
-25
0
25
50
75
100
125
70
8
10
15
20
25
30
35
40
JUNCTION TEMPERATURE(
o
C)
JUNCTION TEMPERATURE(
o
C)
Switch Saturation Voltage
1.7
SATURATION VOLTAGE (V)
SWITCH CURRENT LIMIT (A)
Switch Current Limit
6.0
1.6
1.5
1.4
1 : -40
2 : 25
o
C
3 : 125
o
C
o
C
V
IN
=12V, V
OUT
=5V
5.5
5.0
1
1.3
1.2
3
2.0
3
4
5
2
4.5
4.0
-50
-25
0
25
50
75
100 125
o
SWITCH CURRENT(A)
JUNCTION TEMPERATURE( C)
Operating Quiescent Current
25.0
SUPPLY CURRENT (mA)
Shutdown Quiescent Current
200.0
160.0
CURRENT (uA)
20.0
15.0
10.0
5.0
0.0
-50
-25
0
25
50
75
100
125
JUNCTION
TEMPERATURE(
o
C)
Switch ON
Switch OFF
120.0
80.0
40.0
0.0
1
2
3
V
ON/OFF
=5V
1 : -40
o
C
2 : 25
o
C
3 : 125
o
C
20
30
40
10
SUPPLY VOLOTAGE (V)
5/10
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