ISSUED DATE :2006/03/09
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 T
J
=25 : .
Parameter
Feedback bias current
Oscillator frequency
Oscillator frequency of
short circuit protect
Saturation voltage
Max. duty cycle (ON)
Max. duty cycle (OFF)
Current limit
Output leakage current
Quiescent current
ON/OFF pin logic input
Threshold Voltage
ON/OFF pin Logic input
current
ON/OFF pin input
current
Standby quiescent
current
Thermal Resistance
Symbol
Conditions
V
FB
=1.3V
(adjustable version only)
When current limit occurred and
V
FB
<0.5V, T
A
=25 : .
I
LOAD
=3A No outside circuit
V
FB
=0V force drive on
V
FB
=0V force drive on
V
FB
=12V force drive off
Peak current No outside circuit
V
FB
=0V force drive on
Output=0V
,
No outside circuit
V
FB
=12V force drive off
Output=-1V, V
IN
=22V
V
FB
=12V force drive off
Low (Regulator ON)
High (Regulator OFF)
V
LOGIC
=2.5V ( Regulator OFF)
V
LOGIC
=0.5V ( Regulator ON)
I
FB
F
OSC
F
SCP
V
SAT
DC
Min
-
127/110
5
-
-
-
3.6
-
-
-
-
2.0
-
-
-
-
-
Typ
-10
150
15
1.4
100
0
4.5
-
-5
5
-
-
-
-
-0.1
150
10
50
Max
-50/-100
173/173
25
1.6/1.7
-
-
5.5/6.5
-200
-
10
0.6
-
-0.01
Unit
nA
kHz
kHz
V
%
A
uA
mA
mA
V
I
CL
I
L
I
Q
V
IL
V
IH
I
H
I
L
uA
-1
200
-
-
uA
: /W
I
STBY
ON/OFF pin=5V, V
IN
=12V
JC
JA
Junction to Case
Junction to Ambient with copper
2
area of approximately 2 cm
Unless otherwise specified, V
IN
=12V for 3.3V, 5V, adjustable version and V
IN
=18V for the 12V version.
I
LOAD
=0.5A
Function Description
The TO-252-5L surface mount package tab is designed to be soldering to the copper on a printed circuit board. The copper and the board
are the heat sink for this package and the other heat producing components, such as the catch diode and inductor. The PC board copper
area that the package is soldered to should be at least 0.8 in and ideally should have 2 or more square inches of 2 oz. Additional copper
area improve the thermal characteristics, but with copper areas greater than approximately 6 in , only small improvements in heat
dissipation are realized. If further thermal improvements are needed, double sided, multi-layer PC board with large copper areas and/or
airflow will be recommended. The G5J2596M junction temperature rises above ambient temperature with a 3A load and different input and
output voltages. The data was taken with the circuit operating as a buck-switching regulator with all components mounted on a PC board
to simulate the junction temperature under actual operating conditions. This curve can be used for a quick check for the approximate
junction temperature for various conditions, but be aware that there are many factors that can affect the junction temperature. When load
current higher than 3A are used, double sided or multi-layer PC boards with large copper areas and/or airflow might be needed, especially
for high ambient temperatures and high output voltages.
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.
2
2
G5J2596M
Page: 3/6
GTM [ GTM CORPORATION ]
