4

UC1823A,B/1825A,B

UC2823A,B/2825A,B

UC3823A,B/3825A,B

the UC1823A,B and UC1825A,B; –40°C to +85°C for the UC2823A,B and UC2825A,B; 0°C to +70°C for the UC3823A,B and

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Current Limit/Start Sequence/Fault Section (cont.)

Over Current Threshold

1.14

1.2

1.26

V

ILIM Delay to Output

50

80

ns

Output Section

Output Low Saturation

0.25

0.4

V

1.2

2.2

V

Output High Saturation

1.9

2.9

V

2

3

V

UVLO Output Low Saturation

0.8

1.2

V

Rise/Fall Time

20

45

ns

UnderVoltage Lockout

Start Threshold

UCX823B and X825B only

16

17

V

Stop Threshold

UCX823B and X825B only

9

10

V

UVLO Hysteresis

UCX823B and X825B only

5

6

7

V

Start Threshold

UCX823A and X825A only

8.4

9.2

9.6

V

UVLO Hysteresis

UCX823A and X825A only

0.4

0.8

1.2

V

Supply Current

Startup Current

100

300

µA

Icc

28

36

mA

Note 1:Guaranteed by design. Not 100% tested in production.

OSCILLATOR

The UC3823A,B/3825A,B oscillator is a saw tooth. The

rising edge is governed by a current controlled by the RT

pin and value of capacitance at the CT pin. The falling

edge of the sawtooth sets dead time for the outputs. Se-

lection of RT should be done first, based on desired

maximum duty cycle. CT can then be chosen based on

are:

()

()

RT

V

mA

=

3

10

1 –

()

()

CT

D

RT

F

MAX

=

•

•

16

.

Recommended values for RT range from 1k to 100k.

Oscillator

APPLICATIONS INFORMATION

UDG-95102