Cherry Semiconductor CS52843ED8, CS52843ED14, CS52843EDR8, CS52843EDR14 Datasheet

The CS52843 provides all the nec­essary features to implement off­line fixed frequency current-mode
control with a minimum number
of external components.

The CS52843 incorporates a new
precision temperature-controlled
oscillator to minimize variations in
frequency. An undervoltage lock­out ensures that V

REF

is stabilized

before the output stage is enabled.
In the CS52843 turn on is at 8.4V
and turn off at 7.6V.

Other features include low start-up
current, pulse-by-pulse current lim­iting, and a high-current totem pole
output for driving capacitive loads,
such as gate of a power MOSFET.
The output is low in the off state,
consistent with N-channel devices.

1

Features

■

Optimized for Off-line
Control

■ Internally

Temperature

Compensated Oscillator

■ V

REF

Stabilized before

Output Stage is Enabled

■ Very Low Start-up Current

300 µA (typ)

■ Pulse-by-pulse Current

Limiting

■ Improved Undervoltage

Lockout

■ Double Pulse Suppression

■ 2% 5 Volt Reference

■ High Current Totem Pole

Output

Package Options

CS52843

Current Mode PWM

Control Circuit

CS52843

Description

Block Diagram

Absolute Maximum Ratings

Supply Voltage (I

CC

<30mA) ..........................................................Self Limiting

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

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

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

Analog Inputs (V

FB

, V

SENSE

)...........................................................-0.3V to 5.5V

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

Lead Temperature Soldering

Reflow (SMD styles only)...........60 sec. max above 183°C, 230°C peak

7

8

2

3

4

5

6

COMP

V

FB

Sense

OSC

V

REF

V

CC

V

OUT

Gnd

8L SO Narrow

A Company

®

10

7

14

13

12

8

1

2

3

4

5

6

11

9

COMP

NC

V

FB

NC

Sense

NC

OSC

V

REF

NC
V

CC

VCC Pwr
V

OUT

Pwr Gnd
Gnd

14L SO Narrow

Rev. 12/23/97

Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: [phone] Fax: [phone]

Email: [e-mail]

Web Site: www.cherry-semi.com

V

CC

34V

Gnd

V

FB

COMP

OSC

Sense

Undervoltage Lock-out

V

CC

8.4V/7.6V

Error

Amplifier

2 R

Oscillator

R

­+

R

2.50V

1V

Current

Sensing

Comparator

5.0 Volt

Set/

Reference

Reset

OUTPUT
ENABLE

R

NOR

S

R
PWM

Latch

Internal

Bias

V

Pwr

CC

V

REF

V

OUT

Pwr Gnd

1

2

Electrical Characteristics: -40 ≤ TA ≤ 85˚C; V

CC

= 15V (Note 1); RT = 680Ω; CT = .022µF for triangle mode,

R

T

= 10kΩ; CT = 3.3nF sawtooth mode unless otherwise stated.

CS52843

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

■ Reference Section

Output Voltage TJ = 25˚C, I

REF

= 1mA 4.90 5.00 5.10 V

Line Regulation 12 ≤ V

CC

≤ 25V 6 20 mV

Load Regulation 1 ≤ I

RE F

≤ 20mA 6 25 mV

Temperature Stability (Note 1) 0.2 0.4 mV/˚C

Total Output Variation Line, Load, Temp. (Note 1) 4.82 5.18 V

Output Noise Voltage 10Hz ≤ f ≤ 10kHz, T

J

= 25˚C (Note 1) 50 µV

Long Term Stability TA = 125˚C, 1000 Hrs. (Note 1) 5 25 mV

Output Short Circuit T

A

= 25˚C -30 -100 -180 mA

■ Oscillator Section

Initial Accuracy Sawtooth Mode, T

J

= 25˚C (Note 1) 47 52 57 kHz

Triangle Mode, T

J

= 25˚C 44 52 60 kHz

Voltage Stability 12 ≤ V

CC

≤ 25V 0.2 1.0 %

Temperature Stability Sawtooth Mode T

MIN

≤ TA ≤ T

MAX

5%

Triangle Mode T

MIN

≤ TA ≤ T

MAX

(Note 1) 8 %

Amplitude V

OSC

(peak to peak) 1.7 V

Discharge Current T

J

= 25˚C 7.3 8.3 9.3 mA

T

MIN

≤ TA ≤ T

MAX

6.8 9.8 mA

■ Error Amp Section

Input Voltage V

COMP

= 2.5V 2.42 2.50 2.58 V

Input Bias Current V

FB

= 0V -0.3 -2.0 µA

A

VOL

2 ≤ V

OUT

≤ 4V 65 90 dB

Unity Gain Bandwidth (Note 1) 0.7 1.0 MHz

PSRR 12 ≤ V

CC

≤ 25V 60 70 dB

Output Sink Current V

FB

= 2.7V, V

COMP

= 1.1V 2 6 mA

Output Source Current V

FB

= 2.3V, V

COMP

= 5V -0.5 -0.8 mA

V

OUT

HIGH V

FB

= 2.3V, RL = 15kΩ to Gnd 5 6 V

V

OUT

LOW V

FB

= 2.7V, RL = 15kΩ to V

REF

0.7 1.1 V

■ Current Sense Section

Gain (Notes 2 & 3) 2.85 3.00 3.15 V/V

Maximum Input Signal V

COMP

= 5V (Note 2) 0.9 1.0 1.1 V

PSRR 12 ≤ V

CC

≤ 25V (Note 2) 70 dB

Input Bias Current V

Sense

=0V -2 -10 µA

Delay to Output TJ=25˚C (Note 1) 150 300 ns

■ Output Section

Output Low Level I

SINK

= 20mA 0.1 0.4 V

I

SINK

= 200mA 1.5 2.2 V

Output High Level I

SOURCE

= 20mA 13.0 13.5 V

I

SOURCE

= 200mA 12.0 13.5 V