UC3842A, 43A UC2842A, 43A

3

MOTOROLA ANALOG IC DEVICE DATA

unless otherwise noted.)

UC284XA

UC384XA

Characteristics

Symbol

Min

Typ

Max

Min

Typ

Max

Unit

ERROR AMPLIFIER SECTION

Voltage Feedback Input (VO = 2.5 V)

VFB

2.45

2.5

2.55

2.42

2.5

2.58

V

Input Bias Current (VFB = 2.7 V)

IIB

–

–0.1

–1.0

–

–0.1

–2.0

µA

Open Loop Voltage Gain (VO = 2.0 V to 4.0 V)

AVOL

65

90

–

65

90

–

dB

Unity Gain Bandwidth (TJ = 25°C)

BW

0.7

1.0

–

0.7

1.0

–

MHz

Power Supply Rejection Ratio (VCC = 12 V to 25 V)

PSRR

60

70

–

60

70

–

dB

Output Current

Sink (VO = 1.1 V, VFB = 2.7 V)

Source (VO = 5.0 V, VFB = 2.3 V)

ISink

ISource

2.0

–0.5

12

–1.0

–

–

2.0

–0.5

12

–1.0

–

–

mA

Output Voltage Swing

High State (RL = 15 k to ground, VFB = 2.3 V)

Low State (RL = 15 k to Vref, VFB = 2.7 V)

VOH

VOL

5.0

–

6.2

0.8

–

1.1

5.0

–

6.2

0.8

–

1.1

V

CURRENT SENSE SECTION

Current Sense Input Voltage Gain (Notes 4 & 5)

AV

2.85

3.0

3.15

2.85

3.0

3.15

V/V

Maximum Current Sense Input Threshold (Note 4)

Vth

0.9

1.0

1.1

0.9

1.0

1.1

V

Power Supply Rejection Ratio

VCC = 12 to 25 V (Note 4)

PSRR

–

70

–

–

70

–

dB

Input Bias Current

IIB

–

–2.0

–10

–

–2.0

–10

µA

Propagation Delay (Current Sense Input to Output)

tPLH(in/out)

–

150

300

–

150

300

ns

OUTPUT SECTION

Output Voltage

Low State (ISink = 20 mA)

High State (ISink = 20 mA)

VOL

VOH

–

–

13

12

0.1

1.6

13.5

13.4

0.4

2.2

–

–

–

–

13

12

0.1

1.6

13.5

13.4

0.4

2.2

–

–

V

Output Voltage with UVLO Activated

VCC = 6.0 V, ISink = 1.0 mA

VOL(UVLO)

–

0.1

1.1

–

0.1

1.1

V

Output Voltage Rise Time (CL = 1.0 nF, TJ = 25°C)

tr

–

50

150

–

50

150

ns

Output Voltage Fall Time (CL = 1.0 nF, TJ = 25°C)

tf

–

50

150

–

50

150

ns

UNDERVOLTAGE LOCKOUT SECTION

Startup Threshold

UCX842A

UCX843A

Vth

15

7.8

16

8.4

17

9.0

14.5

7.8

16

8.4

17.5

9.0

V

Minimum Operating Voltage After Turn–On

UCX842A

UCX843A

VCC(min)

9.0

7.0

10

7.6

11

8.2

8.5

7.0

10

7.6

11.5

8.2

V

PWM SECTION

Duty Cycle

Maximum

Minimum

DCmax

DCmin

94

–

96

–

–

0

94

–

96

–

–

0

%

TOTAL DEVICE

Power Supply Current (Note 2)

Startup:

(VCC = 6.5 V for UCX843A,

ICC

–

–

0.5

12

1.0

17

–

–

0.5

12

1.0

17

mA

Power Supply Zener Voltage (ICC = 25 mA)

VZ

30

36

–

30

36

–

V

NOTES: 2. Adjust VCC above the Startup threshold before setting to 15 V.

3. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible

Thigh = +70°C for UC3842A, UC3843A

4. This parameter is measured at the latch trip point with VFB = 0 V.

5. Comparator gain is defined as: AV

∆V Output Compensation

∆V Current Sense Input