DB3 DB4 SMDB3

®

DIAC

FEATURES
■

■

VBO : 32V and 40V
LOW BREAKOVER CURRENT

DO-35
(DB3 and DB4)

DESCRIPTION
Functioning as a trigger diode with a fixed voltage
reference, the DB3/DB4 series can be used in
conjunction with triacs for simplified gate control
circuits or as a starting element in fluorenscent
lamp ballasts.
A new surface mount version is now available in
SOT-23 package, providing reduced space and
compatibility with automatic pick and place
equipment.

2
3
1

SOT-23
(SMDB3)*
Pin 1 and 3 must be shorted
together

ABSOLUTE MAXIMUM RATINGS (limiting values)
Symbol
ITRM

Tstg
Tj

Parameter
Repetitive peak on-state current
tp = 20 µs
F= 120 Hz

Storage temperature range
Operating junction temperature range

Value

Unit

SMDB3

1.00

A

DB3 / DB4

2.00
- 40 to + 125

°C

Note: * SMDB3 indicated as Preliminary spec as product is still in development stage.

October 2001 - Ed: 2B

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DB3 DB4 SMDB3
ELECTRICAL CHARACTERISTICS (Tj = 25°C unless otherwise specified)
Symbol

Parameter

Test Conditions

VBO

Breakover voltage *

C = 22nF **

SMDB3

DB3

DB4

Unit

MIN.

28

28

35

V

TYP.

32

32

40

MAX.

36

36

45

I VBO1 - VBO2 I

Breakover voltage
symmetry

C = 22nF **

MAX.

∆V

Dynamic breakover
voltage *

VBO and VF at 10mA

MIN.

10

5

V

VO

Output voltage *

see diagram 2
(R=20Ω)

MIN.

10

5

V

IBO

Breakover current *

C = 22nF **

MAX.

10

50

µA

see diagram 3

MAX.

0.50

2

µs

VR = 0.5 VBO max

MAX.

1

10

µA

see diagram 2 (Gate)

MIN.

1

0.30

A

tr

Rise time *

IR

Leakage current *

IP

Peak current *

3

V

* Applicable to both forward and reverse directions.
** Connected in parallel to the device.

PRODUCT SELECTOR
VBO

Package

SMDB3

28 - 36

SOT-23

DB3

28 - 36

DO-35

DB4

35 - 45

DO-35

Part Number

ORDERING INFORMATION

SM DB 3
Surface
Mount
Version

Breakover voltage
3: VBO typ = 32V
4: VBO typ = 40V
Diac Series

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DB3 DB4 SMDB3
OTHER INFORMATION
Part Number

Marking

Weight

Base Quantity

Packing Mode

SMDB3

DB3

0.01 g

3000

Tape & Reel

DB3

DB3 (Blue Body Coat)

0.15 g

5000

Tape & Reel

DB4

DB4 (Blue Body Coat)

0.15 g

5000

Tape & Reel

Diagram 1: Voltage - current characteristic curve.

Diagram 2: Test circuit.
10 kΩ

220 V

+ IF

500 kΩ

D.U.T

Rs=0

I

C=0.1µF

50 Hz

P

Vo

10mA

T410
R=20 Ω

-V

IBO
IB

+ V

Diagram 3: Rise time measurement.

0,5 VBO
V
VF

lp
VBO

90 %

- IF

10 %
tr

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DB3 DB4 SMDB3
Fig. 1: Relative variation of VBO versus junction
temperature (typical values).

Fig. 2: Repetitive peak pulse current versus pulse
duration (maximum values).
ITRM(A)

VBO [Tj] / VBO [Tj=25°C]

20.0

1.10
1.05

F=120Hz
Tj initial=25°C

10.0

DB3/DB4

DB3/DB4

1.00
0.95

SMDB3

1.0

SMDB3

0.90
0.85

tp(µs)

Tj(°C)
0.80
25

50

75

100

125

0.1

1

10

100

Fig. 3: Time duration while current pulse is higher
50mA versus C and Rs (typical values).

tp(µs)
40
Tj=25°C

68Ω

35
30

47Ω

25

33Ω

20
15
22Ω

10
10Ω

5
0
10

C(nF)

0Ω

20

50

100

200

500

PACKAGE MECHANICAL DATA (in millimeters)
DO-35

REF.
C

O
/D

4/5

A

C

O
/D

DIMENSIONS
Millimeters

O
/ B

Inches

Min.

Max.

Min.

Max.

A

3.05

4.50

0.120

0.177

B

1.53

2.00

0.060

0.079

C

28.00

D

0.458

1.102
0.558

0.018

0.022

DB3 DB4 SMDB3
PACKAGE MECHANICAL DATA (in millimeters)
SOT-23
REF.

A

E

DIMENSIONS
Millimeters

e
D

e1

B

S

Inches

Min.

Max.

Min.

Max.

A

0.89

1.4

0.035

0.055

A1

0

0.1

0

0.004

B

0.3

0.51

0.012

0.02

c

0.085

0.18

0.003

0.007

D

2.75

3.04

0.108

0.12

e

0.85

1.05

0.033

0.041

e1

1.7

2.1

0.067

0.083

E

1.2

1.6

0.047

0.063

H

2.1

2.75

0.083

0.108

A1

L

H

L

0.6 typ.

0.024 typ.

c

S

0.35

0.65

0.014

0.026

FOOTPRINT
0.9
0.035
1.1
0.043

0.9
0.035

2.35
0.92

1.9
0.075
mm
inch

1.1
0.043

1.45
0.037

0.9
0.035

Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of
use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by
implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to
change without notice. This publication supersedes and replaces all information previously supplied.
STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.

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