UC3842B, 43B UC2842B, 43B

4

MOTOROLA ANALOG IC DEVICE DATA

is the operating ambient temperature range that applies [Note 3], unless otherwise noted.)

UC284XB

UC384XB, BV

Characteristics

Symbol

Min

Typ

Max

Min

Typ

Max

Unit

PWM SECTION

Duty Cycle

Maximum (UC284XB, UC384XB)

Minimum

DC(max)

DC(min)

94

–

–

96

–

–

–

–

0

94

93

–

96

96

–

–

–

0

%

TOTAL DEVICE

Power Supply Current

Startup (VCC = 6.5 V for UCX843B,

Operating (Note 2)

ICC + IC

–

–

0.3

12

0.5

17

–

–

0.3

12

0.5

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.

Tlow =0°C for UC3842B, UC3843B

Thigh = +70°C for UC3842B, UC3843B

0.8

2.0

5.0

8.0

20

50

80

1.0 M

500 k

200 k

100 k

50 k

20 k

10 k

fOSC, OSCILLATOR FREQUENCY (kHz)

VCC = 15 V

TA = 25°C

Figure 1. Timing Resistor

versus Oscillator Frequency

Figure 2. Output Deadtime

versus Oscillator Frequency

1.0 M

500 k

200 k

100 k

50 k

20 k

10 k

fOSC, OSCILLATOR FREQUENCY (kHz)

1.0

2.0

5.0

10

20

50

100

1

2

Figure 3. Oscillator Discharge Current

versus Temperature

Figure 4. Maximum Output Duty Cycle

versus Timing Resistor

7.0

–55

TA, AMBIENT TEMPERATURE (°C)

– 25

0

25

50

75

100

125

7.5

8.0

8.5

9.0

VCC = 15 V

VOSC = 2.0 V

40

0.8

RT, TIMING RESISTOR (kΩ)

1.0

2.0

3.0

4.0

5.0 6.0 7.0 8.0

50

60

70

80

90

100

Idischg = 7.5 mA

VCC = 15 V

CT = 3.3 nF

TA = 25°C

1. CT = 10 nF

2. CT = 5.0 nF

3. CT = 2.0 nF

4. CT = 1.0 nF

5. CT = 500 pF

6. CT = 200 pF

7. CT = 100 pF

5

Idischg = 8.8 mA

7

3

6

4

VCC = 15 V

TA = 25°C