Sanken Electric Co SI-3201S Datasheet

Switching Type Regulator SI-3201S

Features

● Output current of 3A (Ta = 25ºC, VIN = 8 to 18V)

● High efficiency of 82% (VIN = 14V, IO = 2A)

● Requires 5 external components only

● Built-in reference oscillator (60kHz)

● Phase internally corrected

● Output voltage internally corrected

● Built-in overcurrent and thermal protection circuits

● Built-in soft start circuit

Absolute Maximum Ratings

Parameter Symbol Unit ConditionsRatings
Input voltage
Output voltage
SQ terminal voltage with respect

to ground

Power Dissipation

Junction temperature
Storage temperature

Junction to case thermal resistance

Junction to ambient-air thermal
resistance

V

Tstg

V

O, SQ

P
P

IN

I

O

D1

D2

Tj

j-c

j-a

35
3

–1

22

1.8
–40 to +150
–40 to +125

5.5

66.7

V
A

V

W

W
ºC
ºC

ºC/W

ºC/W

With infinite heatsink
Stand-alone

(Ta=25ºC)

Recommended Operating Conditions

Parameter Symbol

Input voltage
Output current
Operating temperature

Top

V

IN

I

O

Electrical Characteristics

Parameter Symbol

Output voltage
Line regulation
Load regulation

1

*

Efficiency
Oscillation frequency
Quiescent circuit current
Overcurrent protection starting

current

Low level voltage

3

*

Soft
start

Source current when low

terminal

Discharge resistance

Notes:
*1. Efficiency is calculated by the following equation:

VO • I

O

= • 100 (%)

VIN • I

*2. A drooping-type overcurrent protection circuit is built in the IC.

IN

*3. An external voltage may not be applied to the soft start terminal. As shown in the diagram to the
right, use this IC in the soft start mode with a capacitor or in the open-collector drive mode with a
transistor. Leave the soft start terminal open when not using it since it is already pulled up in the IC.

V

O

O

LINE

V

O

LOAD

OSC

S

V

SSL

I

SSL

R

DIS

Ratings

min typ max

8

0.5

–40

(VIN = 14V, I

18
3

+85

= 2A, Tj = 25ºC unless otherwise specified)

OUT

Ratings

min typ max

4.80 5.00

5.20

100

50 mV

82

50 60

70 kHzf
10 mAIq

5

3.1

0.2

15 µA

25 35

4

Unit Conditions

V
A

Ta—PD characteristicsºC

Unit Conditions

V

V

mV V

= 8 to 18V

IN

= 0.5 to 3A

I

O

%

I

= 0 A

O

2

AI

*

V

V

= 0.2V

SSL

kΩ

±0.2

4.0

±0.2

7.9

±0.3

(4.6)

1. V

2. SW

3. GND

4. V

5. SS

16.9

IN

OS

(unit: mm)

4.2

2.8

2.6

+0.2
–0.1

0.45

±0.7

3.9

(4.3)

±0.7

8.2

OUT

±0.2

±0.2

±0.1

(2.0)

a: Type No.
b: Lot No.

(17.9)

±0.6

5.0

(8.0)

External Dimensions

±0.2

3.2

±0.2

10.0

a

b

P1.7 •4 =6.8

12345

0.5

±0.15

0.95

+0.2
–0.1

0.85

±0.7±0.7

(Forming No. 1101)

Standard Circuit Diagram

L

V

IN

C

1

C

3

GND GND

C1: 1000µF
C2: 1000µF

a: Internal power supply
b: Thermal protection
c: Reference oscillator
d: Reset
e: Latch & driver

Cautions:
(1) A high-ripple current flows through

type

1000µF or higher capacitors with low internal resistance.

Refer to the respective data books for more information on
reliability and electrical characteristics of the capacitor.

(2)

C

is a capacitor used for soft start.

3

(3)

L

should be a choke coil with a low core loss for switching

1

power supplies.

(4) Use a Schottky barrier diode for

reverse voltage applied to the 2nd terminal (SQ terminal) is
within the maximum ratings (–1V). If you use a fast-recovery
diode, the recovery voltage and the ON forward voltage may
cause a reversed-bias voltage exceeding the maximum ratings
to be applied to the 2nd terminal (SQ terminal). Applying a
reversed-bias voltage exceeding the maximum rating to the
2nd terminal (SQ terminal) may damage the IC.

(5) The 4th terminal (

Since this terminal has a high impedance, connect it to the
positive (+) terminal of

(6) Leave the 5th terminal (soft start terminal) open when not

using it. It is pulled up internally.

(7) To ensure optimum operating environment, connect the high-

frequency current line with minimum wiring length.

SI-3201S

V

IN

a

c

SS

5

V

) is an output voltage detection terminal.

S

SW Tr

CQ

b

d

e

f

g

h

i

GND

3

L1: 250µH
D1: RK46 (Sanken)

f: Comparator
g: Overcurrent protection
h: Error amplifier
i : Reference voltage

C

and C2. Use high-ripple

1

D

and make sure that the

1

C

via the shortest possible route.

2

1

21

D

1

4

V

S

V

O

++

C

2

18

SI-3201S SI-3201S SI-3201S

SS5 SS

C

3

5SS5

C

3

Line Regulation

■

5.10

5.05

5.00

4.95

4.90

Output voltage VO (V)

4.85
0 5 10 15 20 25 30 35

Input voltage V IN (V)

=

I 0A

o

=

1A

=

2A

=

3A

Load Regulation

■

5.15

5.10

5.05

O (V)

5.00

4.95

Output voltage V

4.90

4.85
0

0.5 1.0 1.5 2.0 2.5 3.0

=

V 18V

IN

=

10V

=

7V

Output current I

O (A)

Rise Characteristics

■

6

5

4

O (V)

3

=
=
=

=

I 0A

o

2

1

Output voltage V

0

0

246810

Input voltage V

1A
2A
3A

IN (V)

Efficiency Curve

■

90

80

V 18V

70

IN

60

Efficiency (%)

50

40

0

0.5 1.0 1.5 2.0 2.5 3.0

Output current IO (A)

Ta—PD Characteristics

■

25

With infinite heatsink

20

15

10

5

Power Dissipation PD (W)

=
=

10V

=

7V

With silicone grease
Heatsink: aluminum

Overcurrent Protection Characteristics

■

6

5

=

V 18V

IN

4

O (V)

=

10V

=

7V

3

2

Output voltage V

1

0

0

1.0 2.0 3.0 4.0 5.0

Output current IO (A)

Overcurrent Protection Temperature Characteristics

■

6

5

4

=

+

T 100, 25, 20ºC

C

--

3

2

Output voltage VO (V)

1

0

0 1.0 2.0 3.0 4.0 5.0

Output current IO (A)

0

–40 0 40 80 120 160

Operating temperature Ta (ºC)

19