UC3849B

LINEAR INTEGRATED CIRCUIT

UNISONIC TECHNOLOGIES CO., LTD

4 of 10

www.unisonic.com.tw



PARAMETER

SYMBOL

RATINGS

UNIT

Supply Voltage

36

V

Input Voltage to FB Pin

-0.3~7

V

Input Voltage to CS Pin

-0.3~7

V

Junction Temperature

+150

C

Operating Temperature

-40~+125

°C

Storage Temperature

-50~+150

C

Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.

Absolute maximum ratings are stress ratings only and functional device operation is not implied.



OPERAT I N G RAN GE

PARAMETER

SYMBOL

RATINGS

UNIT

Supply Voltage

9~24

V



PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

SUPPLY SECTION

Start Up Current

2

15

μA

IC Operating Current

0.8

1.8

mA

VCC Zener Clamp Voltage

VCLAMP

IVCC=10mA

32

34

36

V

UNDER-VOLTAGE LOCKOUT SECTION

Start Threshold Voltage

16.5

18

20

V

Min. Operating Voltage

6

7

8

V

CONTROL SECTION

4.9

5.4

V

PWM Input Gain

3

V/V

Burst-Mode Out FB Voltage

1.5

V

Burst-Mode Enter FB Voltage

1.35

V

Normal

60

65

70

KHz

Switch Frequency

Power-Saving

Before enter burst mode

20

KHz

Duty Cycle

70

78

90

%

Frequency Hopping

-9

+9

%

Frequency VDD Stability

10

%

Frequency Temperature Stability

T=-20~100°C

10

%

Feedback Short Current

240

μA

PROTECTION SECTION

25

27

29

V

FB PIN Over Load Protection Threshold

4.2

V

Over Load Protection Delay-Time

60

88

120

mS

Soft Start Time

5

mS

CURRENT LIMITING SECTION

Peak Current Flat Threshold Voltage

≥60%

0.92

V

Peak Current Valley Threshold Voltage

0.60

0.65

0.70

V

Lead Edge Blanking Time

200

350

550

ns

DRIVER OUTPUT SECTION

Output Voltage Low State

1

V

Output Voltage High State

11

V

Output Voltage Rise Time

150

ns

Output Voltage Fall Time

60

ns

RT SECTION

Output Current of RT pin

93

100

107

μA

Threshold Voltage for OTP

0.98

1.04

1.10

V