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ISSUED DATE :2003/07/31
REVISED DATE :2006/03/29E
GJ1084
5A Low Dropout Positive Adjustable or Fixed-Mode Regulator
Description
The GJ1084 is a low dropout positive adjustable or fixed mode regulator with minimum of 5.0A output current
capability. The product is specifically designed to provide well regulated supply for low voltage IC applications
such as high speed bus termination and low current 3.3v logic supply. GJ1084 is also well suited for other
applications such as VGA cards. GJ1084 is guaranteed to have lower than 1.5V dropout at full load current
making it ideal to provide well regulated outputs of 1.25 to 3.3V with 4.7 to 12V input supply.
Features
1.5V maximum dropout at full load current
Built-in thermal shutdown
Output current limiting
Adjustable output voltage or fixed 1.5V,1.8V,2.5V,3.3V,5.0V
Fast transient response
Good noise rejection
Package Dimensions
TO-252
Typical Circuit
REF.
A
B
C
D
E
F
S
Millimeter
Min. Max.
6.40 6.80
5.20 5.50
6.80 7.20
2.40 3.00
2.30 REF.
0.70 0.90
0.60 0.90
REF.
G
H
J
K
L
M
R
Block Diagram
Millimeter
Min. Max.
0.50 0.70
2.20 2.40
0.45 0.55
0 0.15
0.90 1.50
5.40 5.80
0.80 1.20
Pin Descriptions
Name
I/O
Adj (GND)
Vout
O
Vin I
Pin#
1
2
3
Function
Adjustable (Ground only for fixed mode)
The output of the regulator. A minimum of 10uF capacitor must be connected from this pin to
ground to insure stability.
The input pin of regulator. Typically a large storage capacitor is connected from this pin to ground
to insure that the input voltage does not sag below the minimum dropout voltage during the load
transient response. This pin must always be 1.5V higher than Vout in order for the device to
regulate properly.
GJ1084
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Absolute Maximum Ratings
Symbol
Parameter
Vin DC Supply Voltage
PD Power Dissipation
TST Storage Temperature
TOP Operating Junction Temperature Range
ISSUED DATE :2003/07/31
REVISED DATE :2006/03/29E
Ratings
-0.3 to 12
Internally Limited
-65 ~ + 150
0 ~ + 150
Unit
V
Electrical Characteristics
Symbol
VREF
Parameter
GJ1084ADJ
GJ1084-1.5
Output Voltage
Line Regulation
GJ1084-1.8
GJ1084-2.5
GJ1084-3.3
GJ1084-5.0
GJ1084XXX
GJ1084ADJ
Load Regulation
Vo
GJ1084-1.5
GJ1084-1.8
GJ1084-2.5
GJ1084-3.3
GJ1084-5.0
Dropout Voltage
ILIM Current Limit
IMIN Minimum Load Current
IADJ Adjust Pin Current
IQ Quiescent Current
Temperature Stability
Thermal Resistance
JA Junction-to-Ambient(No
heat sink ;No air flow)
Conditions(Notes)
Io=10mA, Tj=25 , (Vin-Vout )=1.5V
Io=10mA, Tj=25 , 3.0V Vin 12V
Io=10mA, Tj=25 , 3.3V Vin 12V
Io=10mA, Tj=25 , 4.0V Vin 12V
Io=10mA, Tj=25 , 4.8V Vin 12V
Io=10mA, Tj=25 , 6.5V Vin 12V
Io=10mA, Vout+1.5V<Vin<12V, Tj=25
Vin=3.3V, 0mA<Io<5A, TJ=25 (Note 1,2)
Vin=3.0V, 0mA<Io<5A, TJ=25 (Note 1,2)
Vin=3.3V, 0mA<Io<5A, TJ=25 (Note 1,2)
Vin=4.0V, 0mA<Io<5A, TJ=25 (Note 1,2)
Vin=5.0V, 0mA<Io<5A, TJ=25 (Note 1,2)
Vin=8.0V, 0mA<Io<5A, TJ=25 (Note 1,2)
Io=5.0A( Vout=1% Vout)
Vin-Vout=5V
Vin=5V (adjustable model)
Vin=12V, Io=10mA
Vin=12V, Io=0mA (fixed model)
Io=10mA
MIN
1.225
1.470
1.764
2.450
3.235
4.900
-
-
-
-
-
-
-
-
5.1
-
-
-
-
-
TYP
1.250
1.500
1.800
2.500
3.300
5.000
-
-
12
15
20
26
40
1.4
-
5
55
-
0.5
MAX
1.275
1.530
1.836
2.550
3.365
5.100
0.2
1
15
18
25
33
50
1.5
-
10
100
12
-
98 -
UNIT
V
V
V
V
V
V
%
%
mV
mV
mV
mV
mV
V
A
mA
uA
mA
%
/W
JC
Thermal Resistance
Junction-to-Case
- 15 -
/W
Note 1: See thermal regulation specifications for changes in output voltage due to heating effects. Line and load regulation are measured
at a constant junction Temperature by low duty cycle pulse testing. Load regulation is measured at the output lead =1/18” from the
package.
Note 2: Line and load regulation are guaranteed up to the maximum power dissipation of 15W. Power dissipation is determined by the
difference between input and output and the output current. Guaranteed maximum power dissipation will not be available over the
full input/output range.
GJ1084
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ISSUED DATE :2003/07/31
REVISED DATE :2006/03/29E
Functional Description
Introduction
The GJ1084 adjustable Low Dropout (LDO) regulator is a 3 terminal device that can easily be programmed with the
addition of two external resistors to any voltages within the range of 1.25V to 2.5V. The GJ1084 only needs 1.5V differential
between Vin and Vout to maintain output regulation, the output voltage tolerances are also extremely tight and they include
the transient response as port of the specification. For example, Intel VRE specification calls for a total of +/-100mV
including initial tolerance, load regulation and 0 to 5.0A load step. The GJ1084 is specifically designed to meet the fast
current transient needs as well as providing an accurate initial voltage, reducing the overall system cost with the need for
fewer output capacitors.
Output Voltage Setting
The GJ1084 can be programmed to any voltages in the range of 1.25V to 5V with the addition of R1 and R2 external
resistors According to the following formula:
GJ1084ADJ
The GJ1084 keeps a constant 1.25V between the output pin and the adjust pin. By placing a resistor R1 across these two
pins a constant current flows through R1, adding to the Iadj current requirement of the GJ1084 is 10mA, R1 is typically
selected to be 121 resistor so that It automatically satisfies the minimum current requirement .Notice that since Iadj is
typically in the range of 55uA it only adds a small error to the output voltage and should only be considered when a very
precise output voltage setting is required. For example, in a typical 3.3V application where R1=121 and R2=200 the
error due to Iadj is only 0.3% of the nominal set point.
Load Regulation
Since the GJ1084 is only a 3 terminal device, it is not possible to provide true remote sensing of the output voltage at the
load.
The best load Regulation is achieved when the bottom side of R2 is connected to the load and the top-side of R1 resistor is
connected directly to the case or the Vout pin of the regulator and not to the load. It is important to note that for high current
applications, this can re-present a significant percentage of the overall load regulation and one must keep the path from the
regulator to the load as short as possible to minimize this effect.
Stability
The GJ1084 requires the use of an output capacitor as part of the frequency compensation in order to make the regulator
stable. For most applications a minimum of 10uF aluminum electrolytic capacitor insures both stability and good transient
response.
Thermal Design
The GJ1084 incorporates an internal shutdown that protects the device when the junction temperature exceeds the
maximum allowable junction temperatures. Although this device can operate with junction temperatures in the range of
150 , it is recommended that the selected heat sink be chosen such that during maximum continuous load operation the
junction temperature is kept below the temperature.
Layout Consideration
The output capacitors must be located as close to the Vout terminal of the device as possible .It is recommended to use a
section of a layer of the PC board as a plane to connect the Vout pin to the output capacitors to prevent any high frequency
oscillation that may result due to excessive trace inductance.
GJ1084
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Performance Characteristics
ISSUED DATE :2003/07/31
REVISED DATE :2006/03/29E
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
GJ1084
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