UNITRODE UC1842A, UC1843A, UC1844A, UC1845A, UC2842A, UC2843A, UC2844A, UC2845A, UC3842A, UC3843A, UC3844A, UC3845A Technical data

Loading...
UNITRODE UC1842A, UC1843A, UC1844A, UC1845A, UC2842A, UC2843A, UC2844A, UC2845A, UC3842A, UC3843A, UC3844A, UC3845A Technical data

5962-8670405PA

application

INFO

available

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

Current Mode PWM Controller

FEATURES

Optimized for Off-line and DC to DC Converters

Low Start Up Current (<0.5mA)

Trimmed Oscillator Discharge Current

Automatic Feed Forward Compensation

Pulse-by-Pulse Current Limiting

Enhanced Load Response Characteristics

Under-Voltage Lockout With Hysteresis

Double Pulse Suppression

High Current Totem Pole Output

Internally Trimmed Bandgap Reference

500kHz Operation

Low RO Error Amp

DESCRIPTION

The UC1842A/3A/4A/5A family of control ICs is a pin for pin compatible improved version of the UC3842/3/4/5 family. Providing the necessary features to control current mode switched mode power supplies, this family has the following improved features. Start up current is guaranteed to be less than 0.5mA. Oscillator discharge is trimmed to 8.3mA. During under voltage lockout, the output stage can sink at least 10mA at less than 1.2V for VCC over 5V.

The difference between members of this family are shown in the table below.

Part #

UVLO On

UVLO Off

Maximum Duty

Cycle

 

 

 

UC1842A

16.0V

10.0V

<100%

UC1843A

8.5V

7.9V

<100%

UC1844A

16.0V

10.0V

<50%

UC1845A

8.5V

7.9V

<50%

BLOCK DIAGRAM

Note 1: A/B A = DIL-8 Pin Number. B = SO-14 Pin Number. Note 2: Toggle flip flop used only in 1844A and 1845A.

SLUS224A - SEPTEMBER 1994 - REVISED APRIL 2002

 

 

 

UC1842A/3A/4A/5A

 

CONNECTION DIAGRAMS

UC2842A/3A/4A/5A

 

 

 

UC3842A/3A/4A/5A

ABSOLUTE MAXIMUM RATINGS (Note 1)

 

 

 

Supply Voltage (Low Impedance Source) . . . .

. . . . . . . . . . 30V

PLCC-20, LCC-20

 

 

Supply Voltage (ICC mA) . . . . . . . . . . . . . . . . .

. . . Self Limiting

(TOP VIEW)

 

 

Output Current. . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . ±1A

Q, L Packages

 

 

Output Energy (Capacitive Load). . . . . . . . . . . .

. . . . . . . . . 5 J

 

 

 

 

 

 

PACKAGE PIN FUNCTION

Analog Inputs (Pins 2, 3). . . . . . . . . . . . . . . . . . .

-0.3V to +6.3V

 

FUNCTION

PIN

Error Amp Output Sink Current . . . . . . . . . . . . .

. . . . . . . 10mA

 

N/C

1

Power Dissipation at TA 25°C (DIL-8) . . . . . . .

. . . . . . . . . 1W

 

Comp

2

Storage Temperature Range. . . . . . . . . . . . . .

- 65°C to +150°C

 

N/C

3-4

 

 

 

VFB

5

Lead Temperature (Soldering, 10 Seconds) . . .

. . . . . . . 300°C

 

 

 

 

 

 

N/C

6

Note 1. All voltages are with respect to Ground, Pin 5. Currents

 

 

 

 

 

 

ISENSE

7

are positive into, negative out of the specified terminal. Consult

 

 

 

 

 

 

N/C

8-9

Packaging Section of Databook for thermal limitations and con-

 

 

 

 

 

 

RT/CT

10

siderations of packages. Pin numbers refer to DIL package only.

 

 

 

 

 

 

N/C

11

 

 

 

Pwr Gnd

12

SOIC-14 (TOP VIEW)

 

 

 

 

 

 

 

Gnd

13

D Package

 

 

 

 

 

 

 

N/C

14

 

 

 

Output

15

 

 

 

N/C

16

 

 

 

VC

17

 

 

 

VCC

18

 

 

 

N/C

19

 

 

 

VREF

20

DIL-8, SOIC-8 (TOP VIEW)

J or N, D8 Package

SOIC-WIDE16 (TOP VIEW)

 

 

DW Package

 

 

 

 

 

 

N/C

 

 

 

 

 

N/C

1

 

 

 

16

N/C

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

15

VREF

COMP

 

 

 

 

 

VCC

 

 

 

 

 

3

 

 

 

14

VFB

 

 

 

 

 

 

 

 

 

 

 

 

4

 

 

 

13

VCC

ISENSE

 

 

 

 

 

 

 

 

 

 

 

 

5

 

 

 

12

OUTPUT

RT/CT

 

 

 

 

 

GND

 

 

 

 

 

6

 

 

 

11

N/C

 

 

 

 

 

 

 

 

 

 

 

 

7

 

 

 

10

PWRGND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

N/C

8

 

 

 

9

N/C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for –55°C TA 125°C for the UC184xA; –40°C TA 125°C for the UC284xAQ; –40°C TA 85°C for the UC284xA; 0 TA 70°C for the UC384xA; VCC = 15V (Note 5); RT = 10k; CT = 3.3nF; TA = TJ; Pin numbers refer to DIL-8.

PARAMETER

TEST CONDITIONS

UC184xA\UC284xA

 

UC384xA

 

UNITS

MIN.

TYP.

MAX.

MIN.

TYP.

MAX.

 

 

 

Reference Section

 

 

 

 

 

 

 

 

 

 

Output Voltage

TJ = 25°C, IO = 1mA

4.95

5.00

5.05

4.90

 

5.00

 

5.10

V

Line Regulation

12 VIN 25V

 

6

20

 

 

6

 

20

mV

Load Regulation

1 IO 20mA

 

6

25

 

 

6

 

25

mV

Temp. Stability

(Note 2, Note 7)

 

0.2

0.4

 

 

0.2

 

0.4

mV/°C

Total Output Variation

Line, Load, Temp.

4.9

 

5.1

4.82

 

 

 

5.18

V

Output Noise Voltage

10Hz f 10kHz

 

 

 

 

 

 

 

 

 

 

TJ = 25°C (Note 2)

 

50

 

 

 

50

 

 

V

Long Term Stability

TA = 125°C, 1000Hrs. (Note 2)

 

5

25

 

 

5

 

25

mV

Output Short Circuit

 

-30

-100

-180

-30

 

-100

 

-180

mA

Oscillator Section

 

 

 

 

 

 

 

 

 

 

Initial Accuracy

TJ = 25°C (Note 6)

47

52

57

47

 

52

 

57

kHz

Voltage Stability

12 VCC 25V

 

0.2

1

 

 

0.2

 

1

%

Temp. Stability

TMIN TA TMAX (Note 2)

 

5

 

 

 

5

 

 

%

Amplitude

VPIN 4 peak to peak (Note 2)

 

1.7

 

 

 

1.7

 

 

V

Discharge Current

TJ = 25°C, VPIN 4 = 2V (Note 8)

7.8

8.3

8.8

7.8

 

8.3

 

8.8

mA

 

VPIN 4 = 2V (Note 8)

7.5

 

8.8

7.6

 

 

 

8.8

mA

Error Amp Section

 

 

 

 

 

 

 

 

 

 

Input Voltage

VPIN 1 = 2.5V

2.45

2.50

2.55

2.42

 

2.50

 

2.58

V

Input Bias Current

 

 

-0.3

-1

 

 

-0.3

 

-2

A

AVOL

2 VO 4V

65

90

 

65

 

90

 

 

dB

Unity Gain Bandwidth

TJ = 25°C (Note 2)

0.7

1

 

0.7

 

1

 

 

MHz

PSRR

12 VCC 25V

60

70

 

60

 

70

 

 

dB

Output Sink Current

VPIN 2 = 2.7V, VPIN 1 = 1.1V

2

6

 

2

 

6

 

 

mA

Output Source Current

VPIN 2 = 2.3V, VPIN 1 = 5V

-0.5

-0.8

 

-0.5

 

-0.8

 

 

mA

VOUT High

VPIN 2 = 2.3V, RL = 15k to ground

5

6

 

5

 

6

 

 

V

VOUT Low

VPIN 2 = 2.7V, RL = 15k to Pin 8

 

0.7

1.1

 

 

0.7

 

1.1

V

Current Sense Section

 

 

 

 

 

 

 

 

 

 

Gain

(Note 3, Note 4)

2.85

3

3.15

2.85

 

3

 

3.15

V/V

Maximum Input Signal

VPIN 1 = 5V (Note 3)

0.9

1

1.1

0.9

 

1

 

1.1

V

PSRR

12 VCC 25V (Note 3)

 

70

 

 

 

70

 

 

dB

Input Bias Current

 

 

-2

-10

 

 

-2

 

-10

A

Delay to Output

VPIN 3 = 0 to 2V (Note 2)

 

150

300

 

 

150

 

300

ns

Output Section

 

 

 

 

 

 

 

 

 

 

Output Low Level

ISINK = 20mA

 

0.1

0.4

 

 

0.1

 

0.4

V

 

ISINK = 200mA

 

15

2.2

 

 

15

 

2.2

V

Output High Level

ISOURCE = 20mA

13

13.5

 

13

 

13.5

 

 

V

 

ISOURCE = 200mA

12

13.5

 

12

 

13.5

 

 

V

Rise Time

TJ = 25°C, CL = 1nF (Note 2)

 

50

150

 

 

50

 

150

ns

Fall Time

TJ = 25°C, CL = 1nF (Note 2)

 

50

150

 

 

50

 

150

ns

UVLO Saturation

VCC = 5V, ISINK = 10mA

 

0.7

1.2

 

 

0.7

 

1.2

V

3

UC1842A/3A/4A/5A

UC2842A/3A/4A/5A

UC3842A/3A/4A/5A

ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for –55°C ≤ TA ≤ 125°C for the UC184xA; –40°C ≤ TA ≤ 125°C for the UC284xAQ; –40°C ≤ TA ≤ 85°C for the UC284xA; 0 ≤ TA ≤ 70°C for the UC384xA; VCC = 15V (Note 5); RT = 10k; CT = 3.3nF; TA = TJ; Pin numbers refer to DIL-8.

PARAMETER

TEST CONDITIONS

UC184xA\UC284xA

 

UC384xA

 

UNITS

MIN.

TYP.

MAX.

MIN.

TYP.

MAX.

 

 

 

Under-Voltage Lockout Section

 

 

 

 

 

 

 

 

 

 

Start Threshold

x842A/4A

15

16

17

14.5

 

16

 

17.5

V

 

x843A/5A

7.8

8.4

9.0

7.8

 

8.4

 

9.0

V

Min. Operation Voltage After

x842A/4A

9

10

11

8.5

 

10

 

11.5

V

Turn On

x843A/5A

7.0

7.6

8.2

7.0

 

7.6

 

8.2

V

PWM Section

 

 

 

 

 

 

 

 

 

 

Maximum Duty Cycle

x842A/3A

94

96

100

94

 

96

 

100

%

 

x844A/5A

47

48

50

47

 

48

 

50

%

Minimum Duty Cycle

 

 

 

0

 

 

 

 

0

%

Total Standby Current

 

 

 

 

 

 

 

 

 

 

Start-Up Current

 

 

0.3

0.5

 

 

0.3

 

0.5

mA

Operating Supply Current

VPIN 2 = VPIN 3 = 0V

 

11

17

 

 

11

 

17

mA

VCC Zener Voltage

ICC = 25mA

30

34

 

30

 

34

 

 

V

Note 2: Ensured by design, but not 100% production tested.

Note 3: Parameter measured at trip point of latch with VPIN2 = 0.

Note 4: Gain defined as: A = VPIN 1 ; 0 VPIN 3 0.8V. VPIN 3

Note 5: Adjust VCC above the start threshold before setting at 15V.

Note 6: Output frequency equals oscillator frequency for the UC1842A and UC1843A. Output frequency is one half oscillator frequency for the UC1844A and UC1845A.

Note 7: “Temperature stability, sometimes referred to as average temperature coefficient, is described by the equation:

Temp Stability = VREF (max ) − VREF (min).VREF (max) and VREF (min) are the maximum & minimum reference voltTJ (max ) − TJ (min)

age measured over the appropriate temperature range. Note that the extremes in voltage do not necessarily occur at the extremes in temperature.”

Note 8: This parameter is measured with RT = 10k to VREF.This contributes approximately 300A of current to the measurement. The total current flowing into the RT/C pin will be approximately 300A higher than the measured value.

Error Amp Configuration

Error Amp can Source and Sink up to 0.5mA, and Sink up to 2mA.

4

+ 7 hidden pages