UNITRODE UC1842A, UC1843A, UC1844A, UC1845A, UC2842A Technical data

...

查询5962-8670405PA供应商

Current Mode PWM Controller

FEATURES DESCRIPTION

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 R

O Error Amp

The UC1842A/3A/4A/5A family of control ICs is a pin for pin compati ble improved version of the UC3842/3/4/5 family. Providing the nec essary features to control current mode switched mode power supplies, this family has the following improved features. Start up cur rent 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 V

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

Part # UVLO On UVLO Off

UC1842A 16.0V 10.0V <100%

UC1843A 8.5V 7.9V <100%

UC1844A 16.0V 10.0V <50%

UC1845A 8.5V 7.9V <50%

application

INFO

available

UC1842A/3A/4A/5A UC2842A/3A/4A/5A UC3842A/3A/4A/5A

CC over 5V.

Maximum Duty

Cycle

BLOCK DIAGRAM

Note 1: 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

A/B

CONNECTION DIAGRAMS

ABSOLUTE MAXIMUM RATINGS (Note 1)

Supply Voltage (Low Impedance Source) . . . . . . . . . . . . . . 30V

Supply Voltage (I

Output Current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±1A

Output Energy (Capacitive Load). . . . . . . . . . . . . . . . . . . . . 5µJ

Analog Inputs (Pins 2, 3). . . . . . . . . . . . . . . . . . . -0.3V to +6.3V

Error Amp Output Sink Current . . . . . . . . . . . . . . . . . . . . 10mA

Power Dissipation at T

Storage Temperature Range. . . . . . . . . . . . . . -65°C to +150°C

Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300°C

Note 1. All voltages are with respect to Ground, Pin 5. Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and con siderations of packages. Pin numbers refer to DIL package only.

SOIC-14 (TOP VIEW) D Package

CC mA) . . . . . . . . . . . . . . . . . . . . Self Limiting

A ≤ 25°C (DIL-8) . . . . . . . . . . . . . . . . 1W

PLCC-20, LCC-20 (TOP VIEW) Q, L Packages

UC1842A/3A/4A/5A UC2842A/3A/4A/5A UC3842A/3A/4A/5A

PACKAGE PIN FUNCTION

FUNCTION PIN

N/C Comp 2 N/C 3-4 VFB 5 N/C 6 ISENSE 7 N/C 8-9 RT/CT 10 N/C 11 Pwr Gnd 12 Gnd 13 N/C 14 Output 15 N/C 16 VC 17 VCC 18 N/C 19 VREF 20

SOIC-WIDE16 (TOP VIEW) DW Package

N/C

COMP

ISENSE

RT/CT

VFB

N/C

DIL-8, SOIC-8 (TOP VIEW) J or N, D8 Package

N/C

VREF

VCC

OUTPUT

GND

PWRGND

N/C

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 ≤ T (Note 5); R

T = 10k; CT = 3.3nF; TA =TJ; Pin numbers refer to DIL-8.

A ≤ 125°C for the UC284xAQ; –40°C ≤ TA ≤ 85°C for the UC284xA; 0 ≤ TA ≤ 70°C for the UC384xA; VCC = 15V

PARAMETER TEST CONDITIONS

UC184xA\UC284xA UC384xA

MIN. TYP. MAX. MIN. TYP. MAX.

UNITS

Reference Section

Output Voltage T Line Regulation 12 ≤ V Load Regulation 1 ≤ I

J = 25°C, IO = 1mA 4.95 5.00 5.05 4.90 5.00 5.10 V

IN 25V 6 20 6 20 mV

O ≤ 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

J = 25°C (Note 2) 50 50 µV

Long Term Stability T

A = 125°C, 1000Hrs. (Note 2) 5 25 5 25 mV

Output Short Circuit -30 -100 -180 -30 -100 -180 mA

Oscillator Section

Initial Accuracy T Voltage Stability 12 ≤ V Temp. Stability T Amplitude V Discharge Current T

J = 25°C (Note 6) 47 52 57 47 52 57 kHz

CC ≤ 25V 0.2 1 0.2 1 % MIN ≤ TA ≤ TMAX (Note 2) 5 5 % PIN 4 peak to peak (Note 2) 1.7 1.7 V J = 25°C, VPIN 4 = 2V (Note 8) 7.8 8.3 8.8 7.8 8.3 8.8 mA PIN 4 = 2V (Note 8) 7.5 8.8 7.6 8.8 mA

Error Amp Section

Input Voltage V

PIN 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

VOL 2 ≤ VO ≤ 4V 65 90 65 90 dB

A Unity Gain Bandwidth T PSRR 12 ≤ V Output Sink Current V Output Source Current V

OUT High VPIN 2 = 2.3V, RL = 15k to ground 5 6 5 6 V

OUT Low VPIN 2 = 2.7V, RL = 15k to Pin 8 0.7 1.1 0.7 1.1 V

J = 25°C (Note 2) 0.7 1 0.7 1 MHz

CC ≤ 25V 60 70 60 70 dB PIN 2 = 2.7V, VPIN 1 = 1.1V 2 6 2 6 mA PIN 2 = 2.3V, VPIN 1 = 5V -0.5 -0.8 -0.5 -0.8 mA

Current Sense Section

Gain (Note 3, Note 4) 2.85 3 3.15 2.85 3 3.15 V/V Maximum Input Signal V PSRR 12 ≤ V

PIN 1 = 5V (Note 3) 0.9 1 1.1 0.9 1 1.1 V

CC ≤ 25V (Note 3) 70 70 dB

Input Bias Current -2 -10 -2 -10 Delay to Output V

PIN 3 = 0 to 2V (Note 2) 150 300 150 300 ns

Output Section

Output Low Level I

Output High Level I

Rise Time T Fall Time T UVLO Saturation V

SINK = 20mA 0.1 0.4 0.1 0.4 V SINK = 200mA 15 2.2 15 2.2 V

SOURCE = 20mA 13 13.5 13 13.5 V SOURCE = 200mA 12 13.5 12 13.5 V

J = 25°C, CL = 1nF (Note 2) 50 150 50 150 ns J = 25°C, CL = 1nF (Note 2) 50 150 50 150 ns CC = 5V, ISINK = 10mA 0.7 1.2 0.7 1.2 V

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 ≤ T (Note 5); R

T = 10k; CT = 3.3nF; TA =TJ; Pin numbers refer to DIL-8.

A ≤ 125°C for the UC284xAQ; –40°C ≤ TA ≤ 85°C for the UC284xA; 0 ≤ TA ≤ 70°C for the UC384xA; VCC = 15V

PARAMETER TEST CONDITIONS

UC184xA\UC284xA UC384xA

MIN. TYP. MAX. MIN. TYP. MAX.

UNITS

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 V

CC Zener Voltage ICC = 25mA 30 34 30 34 V

PIN 2 =VPIN 3 = 0V 11 17 11 17 mA

Note 2: Ensured by design, but not 100% production tested. Note 3: Parameter measured at trip point of latch with V

VPIN

∆

Note 4: Gain defined as:

Note 5: Adjust V

above the start threshold before setting at 15V.

VPIN

∆

PIN 3

PIN2

0.8V.

= 0.

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

TJ max TJ min

−

() ()

−

() ()

REF

(max) and V

REF

(min) are the maximum & minimum reference volt-

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 R The total current flowing into the R

T/Cpin will be approximately 300

= 10k to V

REF

.This contributes approximately 300 A of current to the measurement.

A higher than the measured value.

Error Amp Configuration

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

+ 7 hidden pages