UC3873

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

4 of 10

www.unisonic.com.tw

QW-R103-068. D



PARAMETER

SYMBOL

RATINGS

UNIT

Supply Voltage

30

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.



OPERATING RANGE

PARAMETER

SYMBOL

RATINGS

UNIT

Supply Voltage

10 ~ 24

V



PARAMETER

SYMBOL

TEST CONDITIONS

MIN

TYP

MAX

UNIT

SUPPLY SECTION

Start Up Current

2.5

20

μA

IC Operating current

1.5

2.5

mA

15

mA

UNDER-VOLTAGE LOCKOUT SECTION

Start Threshold Voltage

12.5

13.8

14.5

V

Min. Operating Voltage

7.5

8.2

9.5

V

Hysteresis

5.6

V

CONTROL SECTION

5

V

PWM Input Gain

3

V/V

Burst-Mode Out FB Voltage

1.6

V

Reduce-Frequency end FB Voltage

2.4

V

Burst-Mode Enter FB Voltage

1.5

V

Switch Frequency

Normal

60

65

70

KHz

Power-Saving

Before enter burst mode

22

KHz

Duty Cycle

76

%

Frequency Hopping

-4

+4

%

Frequency VDD Stability

5

%

Frequency Temperature Stability

T=-20~100°C

1.5

5

%

Feedback Resistor

25

KΩ

PROTECTION SECTION

28

V

FB PIN Over Load Protection Threshold

4.4

V

Over Load Protection Delay-Time

55

mS

Soft start time

3

mS

CURRENT LIMITING SECTION

Peak Current Flat Threshold Voltage

0.92

V

Peak Current Valley Threshold Voltage

0.80

V

Lead Edge Blanking Time

300

ns

DRIVER OUTPUT SECTION

Output Voltage Low State

0.8

V

Output Voltage High State

8

V

Output Voltage Rise Time

500

ns

Output Voltage Fall Time

160

ns

RT SECTION

Output current of RT pin

95

100

105

uA

Threshold voltage for OTP

0.95

1

1.05

V