GTM GSC2596M

ISSUED DATE :2006/03/08
REVISED DATE :2006/05/17B
GSC2596M
150 KHz, 2A PWM Step-Down DC/DC Converter
Description
The GSC2596M series of regulators are monolithic integrated circuit that provides all active functions for a step-down (buck) switching
regulator, capable of driving 2A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3v, 5v,
12v and an adjustable output version. The GSC2596M series operate at a switching frequency of 150 kHz; thus allowing smaller sized
filter components than what would be needed with lower frequency switching regulators. The chips are available in a standard 8-lead
SOP-8 package. Other feature include a guaranteed 4% to tolerance on output voltage under specified input voltages and output load
conditions. The 150 kHz 15% is on the oscillator frequency. External shutdown is included, featuring 80uA (Typ.) standby current. The
output switch includes cycle-by cycle current limiting, as well as thermal shutdown for full protection under fault conditions.
Features
3.3V, 5.0V, 12V and adjustable output versions
Guaranteed 2A output current
Operating voltage can be up to 22V
150kHz fixed frequency internal oscillator
Built-in TTL On/Off control
TTL Shutdown Capability
Uses readily available standard inductors
Thermal shutdown and current limit protection
Applications
High-efficiency step-down regulator
One-ch switching regulators simple
Positive to negative converter
Package Dimensions
REF.
A
B
C
D
E
F
Millimeter
Min.
Max.
5.80
4.80
3.80
0°
0.40
0.19
6.20
5.00
4.00
8°
0.90
0.25
REF.
M
H
L
J
K
G
Millimeter
Min.
Max.
0.10
0.25
0.35
0.49
1.35
1.75
0.375 REF.
45°
1.27 TYP.
Block Diagram
GSC2596M
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ISSUED DATE :2006/03/08
REVISED DATE :2006/05/17B
Pin Function
Pin Name
Pin#
Function
This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor
must be present at this pin to minimize voltage transients and to supply the switching current
needed by regulator.
Internal switch. The voltage at this pin switches between (+V IN - V SAT) and approximately -0.5V,
with a duty cycle of approximately V OUT/V IN. To minimize coupling to sensitive circuitry, the PC
board copper area connected to this pin should be keep to a minimum.
VIN
1
Output
2
Feedback(FB)
3
Senses the regulated output voltage to complete the feedback loop.
4
Allows the switching regulator circuit to be shutdown using logic level signals. Thus drop the total
input supply current to approximately 150 A. Pulling this pin below a threshold voltage of
approximately 1.3V turns the regulator on, and pulling this pin above 1.3V (up to a maximum of
18V) shuts the regulator down. If this shutdown feature is not needed, ON/OFF pin can be wired to
the ground pin.
ON/OFF(SD)
Ground
5,6,7,8
Circuit ground
Absolute Maximum Ratings
Parameter
Symbol
VCC
VSD
VFB
VOUT
PD
TST
TOP
VOP
Supply Voltage
ON/OFF Pin Input Voltage
Feedback Pin Voltage
Output Voltage to ground
Power Dissipation
Storage Temperature
Operating temperature
Operating Voltage
Ratings
24
-0.3 ~ +18
-0.3 ~ +18
-1
Internally Limited
-65 ~ +150
-40 ~ +125
+4.5 ~ +22
Unit
V
V
V
V
W
V
GSC2596M Electrical Characteristics
Specifications in boldface type are for full operating temperature range. The other type are for TJ=25
Parameter
Output Feedback
Symbol
VFB
Efficiency
Conditions
5 VIN 22V, 0.2A ILOAD 2A
VOUT=3V
VIN=12V, ILOAD=2A, VOUT=3V
.
Min
Typ
Max
Unit
1.180/1.168
1.230
1.280/1.292
V
76
%
GSC2596M-33 Electrical Characteristics
Specifications in boldface type are for full operating temperature range. The other type are for TJ=25
Parameter
Output Feedback
Symbol
VFB
Efficiency
Conditions
5.5V VIN 22V
0.2A ILOAD 2A
VIN=12V, ILOAD=2A
.
Min
Typ
Max
Unit
3.168/3.135
3.3
3.432/3.465
V
78
%
GSC2596M-50 Electrical Characteristics
Specifications in boldface type are for full operating temperature range. The other type are for TJ=25
Parameter
Output Feedback
Symbol
VFB
Efficiency
Conditions
8V VIN 22V
0.2A ILOAD 2A
VIN=12V, ILOAD=2A
.
Min
Typ
Max
Unit
4.80/4.75
5.0
5.20/5.25
V
83
%
GSC2596M-12 Electrical Characteristics
Specifications in boldface type are for full operating temperature range. The other type are for TJ=25
Parameter
Output Feedback
Efficiency
GSC2596M
Symbol
VFB
Conditions
15V VIN 22V
0.2A ILOAD 2A
VIN=16V, ILOAD=2A
.
Min
Typ
Max
Unit
11.52/11.40
12
12.48/12.60
V
90
%
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ISSUED DATE :2006/03/08
REVISED DATE :2006/05/17B
All Output Voltage Version Electrical Characteristics
Specifications in boldface type are for full operating temperature range. The other type are for TJ=25
Parameter
Feedback bias current
Oscillator frequency
Symbol
IFB
Conditions
VFB=1.3V (adjustable version only)
FOSC
.
Min
127/110
Typ
-10
150
Max
-50/-100
173/173
Unit
nA
kHz
Oscillator frequency of
short circuit protect
FSCP
When current limit occurred and
VFB<0.5V, TA=25 .
5
15
25
kHz
Saturation voltage
VSAT
ILOAD=2A No outside circuit
VFB=0V force drive on
-
1.25
1.4/1.5
V
VFB=0V force drive on
VFB=12V force drive off
-
100
0
-
%
3
-
-
A
-
-
-200
uA
-
10
mA
mA
2.0
-5
5
-
Max. duty cycle (ON)
Max. duty cycle (OFF)
DC
Current limit
ICL
Output leakage current
IL
IQ
Peak current No outside circuit
VFB=0V force drive on
Output=0V, No outside circuit
VFB=12V force drive off
Output=-1V, VIN=22V
VFB=12V force drive off
ON/OFF pin logic input
VIL
Low (Regulator ON)
Threshold Voltage
ON/OFF pin Logic input
current
VIH
High (Regulator OFF)
IH
VLOGIC=2.5V ( Regulator OFF)
-
IL
VLOGIC=0.5V ( Regulator ON)
-
-0.1
-1
-
150
200
-
15
-
-
70
-
Quiescent current
ON/OFF pin input
current
Standby quiescent
current
ISTBY ON/OFF pin=5V, VIN=12V
JC
Thermal Resistance
JA
Junction to Case
Junction to Ambient with copper
2
area of approximately 3 in
-
0.6
V
-0.01
uA
uA
/W
Unless otherwise specified, V IN=12V for 3.3V, 5V, adjustable version and V IN=18V for the 12V version. ILOAD=0.5A
Function Description
The SOP-8 package needs a heat sink under most conditions. The size of the heat sink depends on the input voltage, the output voltage,
the load current and the ambient temperature. The GSC2596M junction temperature rises above ambient temperature with a 2A load and
different input and output voltages. The data for these curves was taken with the GSC2596M operating as a buck-switching regulator in an
ambient temperature of 25
(still air). These temperature rise numbers are all approximate and there are many factors that can affect
these temperatures. Higher ambient temperatures require more heat sinking.
For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper should be used in the board
layout. (One exception to this is the output (switch) pin, which should not have large areas of copper.) Large areas of copper provide the
best transfer of heat (lower thermal resistance) to the surrounding air, and moving air lowers the thermal resistance even further.
Package thermal resistance and junction temperature rise numbers are all approximate, and there are many factors will affect these
numbers. Some of these factors include board size, shape, thickness, position, location and even board temperature. Other factors are,
trace width, total printed circuit copper area, copper thickness, single or double-sided, multi-layer board and the amount of solder on the
board. The effectiveness of the PC board to dissipate heat also depends on the size, quantity and spacing of other components on the
board, as well as the surrounding air is still or moving. Furthermore, some of these components such as the catch diode will add heat to
the PC board and the heat can vary as the input voltage changes. For the inductor, depending on the physical size, type of core material
and the DC resistance, it could either act as a heat sink taking heat away from the board, or it could add heat to the board.
GSC2596M
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ISSUED DATE :2006/03/08
REVISED DATE :2006/05/17B
Typical Application Circuit
(1)Fixed Type Circuit
(2)Adjustable Type Circuit
(3)Delay Start Circuit
GSC2596M
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ISSUED DATE :2006/03/08
REVISED DATE :2006/05/17B
Typical Performance Characteristics
GSC2596M
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ISSUED DATE :2006/03/08
REVISED DATE :2006/05/17B
Important Notice:
All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of GTM.
GTM reserves the right to make changes to its products without notice.
GTM semiconductor products are not warranted to be suitable for use in life-support Applications, or systems.
GTM assumes no liability for any consequence of customer product design, infringement of patents, or application assistance.
Head Office And Factory:
Taiwan: No. 17-1 Tatung Rd. Fu Kou Hsin-Chu Industrial Park, Hsin-Chu, Taiwan, R. O. C.
TEL : 886-3-597-7061 FAX : 886-3-597-9220, 597-0785
China: (201203) No.255, Jang-Jiang Tsai-Lueng RD. , Pu-Dung-Hsin District, Shang-Hai City, China
TEL : 86-21-5895-7671 ~ 4 FAX : 86-21-38950165
GSC2596M
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