Cherry Semiconductor CS51033YN8, CS51033YDR8, CS51033YD8 Datasheet

1

Features

■ 1A Totem Pole Output

Driver

■ High Speed Oscillator

(700kHz max)

■ No Stability

Compensation Required

■ Lossless Short Circuit

Protection

■ 2% Precision Reference

■ Programmable Soft Start

Package Options

CS51033

Fast PFET Buck Controller

Does Not Require Compensation

CS51033

Description

The CS51033 is a switching con­troller for use in DC-DC converters.
It can be used in the buck topology
with a minimum number of exter­nal components. The CS51033 con­sists of a 1.0A power driver for con­trolling the gate of a discrete P­channel transistor, fixed frequency
oscillator, short circuit protection
timer, programmable soft start, pre­cision reference, fast output voltage
monitoring comparator, and output
stage driver logic with latch.

The high frequency oscillator
allows the use of small inductors
and output capacitors, minimizing
PC board area and systems cost.
The programmable soft start
reduces current surges at start up.
The short circuit protection timer
significantly reduces the PFET duty
cycle to approximately 1/30 of its
normal cycle during short circuit
conditions.

The CS51033 is available in 8L SO
and 8L PDIP plastic packages.

Typical Application Diagram

V

GATE

PGnd

C

OSC

Gnd

V

C

CS
V

CC

V

FB

8 Lead SO Narrow & PDIP

A Company

®

Rev. 2/13/98

Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: [phone] Fax: [phone]

Email: [e-mail]

Web Site: www.cherry-semi.com

3.3V

IN

100µF

C

1µF

C

IN

R

C

10Ω

C

100µF

3

2

D

2

1N4148

1N4148

V

CC

C

OSC

Gnd

D

3

CS51033

PGnd

1N5818

C

OSC

150pF

D

4

C

1

0.1µF

R

V

FB

CS

0.1µF

CS

10Ω

0.01µF

G

IRF 7404

4.7µH

100

.1µF

D

1

1N5821

C

100µF

V

U1

C

V

GATE

1.5V

OUT

@3Amp

C

4

0

0.1µF

100µF

1

Gnd

NOTE: Capacitors C
caps used for noise reduction.

, C3 and C4 are low ESR tantalum

2

1.5k

R

A

300

R

B

Gnd

Power Supply Voltage, VCC..........................................................................................................................................................5V

Driver Supply Voltage, V

C

..........................................................................................................................................................20V

Driver Output Voltage, V

GATE

...................................................................................................................................................20V

C

OSC

, CS, VFB(Logic Pins) ............................................................................................................................................................5V

Peak Output Current................................................................................................................................................................. 1.0A

Steady State Output Current ................................................................................................................................................200mA

Operating Junction Temperature, TJ..................................................................................................................................... 150°C

Storage Temperature Range, TS...................................................................................................................................-65 to 150°C

ESD (Human Body Model).........................................................................................................................................................2kV

Lead Temperature Soldering

Wave Solder (through hole styles only) .....................................................................................10 sec. max, 260°C peak

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

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

2

CS51033

Absolute Maximum Ratings

Electrical Characteristics: Specifications apply for 3.135 ≤ VCC≤ 3.465V, 3V ≤ VC≤ 16V,

-40°C ≤ TA≤ 125°C, -40°C ≤ TJ≤ 125°C, unless otherwise specified.

■ Oscillator V

FB

= 1.2V

Frequency C

OSC

= 470pF 160 200 240 kHz

Charge Current 1.4V < V

COSC

< 2V 110 µA

Discharge Current 2.7V > V

COSC

> 2V 660 µA

Maximum Duty Cycle 1 – (t

OFF/tON

) 80.0 83.3 %

■ Short Circuit Timer V

FB

= 1.0V; CS = 0.1µF; V

COSC

= 2V

Charge Current 1V < V

CS

< 2V 175 264 325 µA

Fast Discharge Current 2.55V > V

CS

> 2.4V 40 66 80 µA

Slow Discharge Current 2.4V > V

CS

> 1.5V 4 6 10 µA
Start Fault Inhibit Time 0.70 0.85 1.40 ms
Valid Fault Time 2.6V > V

CS

> 2.4V 0.2 0.3 0.45 ms
GATE Inhibit Time 2.4V > V

CS

> 1.5V 9 15 23 ms
Duty Cycle 2.5 3.1 4.6 %

■ CS Comparator V

FB

= 1V

Fault Enable CS Voltage 2.5 V
Max. CS Voltage VFB= 1.5V 2.6 V
Fault Detect Voltage VCSwhen GATE goes high 2.4 V
Fault Inhibit Voltage Minimum V

CS

1.5 V

Hold Off Release Voltage V

FB

= 0V 0.4 0.7 1.0 V

Regulator Threshold V

CS

= 1.5V 0.725 0.866 1.035 V

Voltage Clamp

■ V

FB

Comparator V

COSC

= VCS= 2V

Regulator Threshold Voltage TJ= 25°C (Note 1) 1.225 1.250 1.275 V

TJ= -40 to 125°C 1.210 1.250 1.290 V

Fault Threshold Voltage TJ= 25°C (Note 1) 1.12 1.15 1.17 V

TJ= -40 to 125°C 1.10 1.15 1.19 V
Threshold Line Regulation 3.135V ≤ VCC≤ 3.465 6 15 mV
Input Bias Current VFB= 0V 1 4 µA
Voltage Tracking (Regulator Threshold Voltage - 70 100 120 mV

Fault Threshold Voltage)
Input Hysteresis Voltage 4 20 mV

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

CS51033

3

Package Pin Description

PACKAGE PIN # PIN SYMBOL FUNCTION

Electrical Characteristics: Specifications apply for 3.135 ≤ VCC≤ 3.465V, 3V ≤ VC≤ 16V,

-40°C ≤ TJ≤ 125°C, unless otherwise specified.

8L SO Narrow & PDIP

1V

GATE

Driver pin to gate of external PFET.
2 PGnd Output power stage ground connection.
3C

OSC

Oscillator frequency programming capacitor.
4 Gnd Logic ground.
5V

FB

Feedback voltage input.
6V

CC

Logic supply voltage.
7 CS Soft start and fault timing capacitor.
8V

C

Driver supply voltage.

■ Power Stage V

C

= 10V; VFB= 1.2V

GATE DC Low Saturation V

COSC

= 1V; 200mA Sink 1.2 1.5 V

Voltage
GATE DC High Saturation V

COSC

= 2.7V; 200mA Source; VC= V

GATE

1.5 2.1 V

Voltage
Rise Time C

GATE

= 1nF; 1.5V < V

GATE

< 9V 25 60 ns

Fall Time C

GATE

= 1nF; 9V > V

GATE

> 1.5V 25 60 ns

■ Current Drain

I

CC

3.135V < VCC< 3.465V, Gate switching 3.5 6.0 mA

I

C

3V < VC< 16V, Gate non-switching 2.7 4.0 mA

Note1: Guaranteed by design not 100% tested in production.