Cherry Semiconductor CS51031YN8, CS51031YDR8, CS51031YD8 Datasheet
1
Features
■ 1A Totem Pole Output
Driver
■ High Speed Oscillator
(700kHz max)
■ No Stability
Compensation Required
■ Lossless Short Circuit
Protection
■ V
CC
Monitor
■ 2% Precision Reference
■ Programmable Soft Start
Package Options
CS51031
Fast PFET Buck Controller
Does Not Require Compensation
CS51031
Description
The CS51031 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 CS51031 consists of a VCCmonitor for controlling the state of the device, 1.0A
power driver for controlling the
gate of a discrete P-channel 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 duty cycle
to approximately 1/30 of its cycle
during short circuit conditions.
The CS51031 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
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
A Company
¨
Rev. 2/13/98
5V - 12V
C
OSC
150pF
V
GATE
V
PGnd
C
Gnd
C
IN
47mF
V
GATE
CS51031
OSC
C
CS
V
CC
V
FB
20W
MP
IRF7416
MBRS360
D
1
RV
10W
CV
100mF
.01mF
CC
CC
100
CS
0.1mF
R
B
2.5kW
L
4.7mH
1
V
O
3.3V @ 3A
1
R
1.5kW
C
A
RR
0.1mF
C
O
100mF ´ 2
Power Supply Voltage, VCC........................................................................................................................................................20V
Driver Supply Voltage, VC..........................................................................................................................................................20V
Driver Output Voltage, V
GATE
...................................................................................................................................................20V
C
OSC
, CS, VFB(Logic Pins) ............................................................................................................................................................6V
Peak Output Current................................................................................................................................................................. 1.0A
Steady State Output Current ................................................................................................................................................200mA
Operating Junction Temperature, TJ..................................................................................................................................... 150¡C
Operating Temperature Range, TA............................................................................................................................-40¡ to 125¡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
CS51031
Absolute Maximum Ratings
Electrical Characteristics: Specifications apply for 4.5 ² VCC² 16V, 3V ² VC² 16V,
-40¡C ² TJ² 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 Ð (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 0V < V
CS
< 2.5V 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
Fault 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 VFB= 0V 0.4 0.7 1.0 V
Regulator Threshold VCS= 1.5V 0.725 0.866 1.035 V
Voltage Clamp
■ V
FB
Comparators 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 4.5V ² VCC² 16V 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
CS51031
3
Electrical Characteristics: Specifications apply for 4.5 ² VCC² 16V, 3V ² VC² 16V, -40¡C ² TJ² 125¡C,
unless otherwise specified.
Package Pin Description
PACKAGE PIN # PIN SYMBOL FUNCTION
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.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
■ Power Stage V
CC
= VC= 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
■ V
CC
Monitor
Turn On Threshold 4.200 4.400 4.600 V
Turn Off Threshold 4.085 4.300 4.515 V
Hysteresis 65 130 200 mV
■ Current Drain
I
CC
4.5V < VCC< 16V, Gate switching 4.5 6.0 mA
I
C
3V < VC< 16V, Gate non-switching 2.7 4.0 mA
Shutdown I
CC
VCC= 4, 500 900 µA
Note 1: Guaranteed by design not 100% tested in production.
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