ISSUED DATE :2005/06/01
REVISED DATE :2006/06/01B
GE1085
3A Low Dropout Positive Adjustable or Fixed-Mode Regulator
The GE1085 is a low dropout positive adjustable or fixed-mode regulator with minimum of 3A 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. GE1085 is also well suited for other
applications such as VGA cards. GE1085 is guaranteed to have <1.4V dropout at full load current making it
ideal to provide well-regulated outputs of 1.25 to 5.0V with 4.7 to 12V input supply by different output voltage.
Description
Features
&
3-Terminal Adjustable or fixed 1.5V,1.8V,2.5V,3.3V,5.0V
Maximum Dropout at Full Load current
&
Fast Transient response
&Built-in Thermal Shutdown
&Output current limiting
&
1.4V
Package Dimensions
REF.
A
b
c
D
E
L4
L5
Millimeter
Min.
Max.
4.40
4.80
0.76
1.00
0.36
0.50
8.60
9.00
9.80
10.4
14.7
15.3
6.20
6.60
REF.
c1
b1
L
e
L1
Ø
A1
Millimeter
Min.
Max.
1.25
1.45
1.17
1.47
13.25
14.25
2.54 REF.
2.60
2.89
3.71
3.96
2.60
2.80
Typical Circuit
3.3V/3A
2.5V/3A
Block Diagram
GE1085
Page: 1/4
ISSUED DATE :2005/06/01
REVISED DATE :2006/06/01B
Pin Descriptions
Name
Adj (GND)
Vout
O
I/O
Pin#
1
2
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 1.4V higher than Vout in order for the device to
regulate properly.
Function
Vin
I
3
Absolute Maximum Ratings
Symbol
V
in
P
D
T
ST
T
OP
DC Supply Voltage
Power Dissipation
Storage Temperature
Operating Junction Temperature Range
Parameter
Ratings
-0.3 to 12
Internally Limited
-65 ~ + 150
0 ~ + 150
:
:
Unit
V
Electrical Characteristics
Parameter
Reference Voltage
GE1085-ADJ
GE1085-1.5
GE1085-1.8
Output Voltage
GE1085-2.5
GE1085-3.3
GE1085-5.0
Line Regulator
GE1085-XXX
GE1085ADJ
GE1085-1.5
Load Regulation
GE1085-1.8
GE1085-2.5
GE1085-3.3
GE1085-5.0
Dropout Voltage
(Vin-Vout)
Current Limit
Minimum Load Current
Adjust Pin Current
Quiescent Current
Thermal Regulation
Ripple Rejection
Temperature Stability
Thermal Resistance
Junction-to-Ambient
Thermal Resistance
Junction-to-Case
GE1085-XXX
GE1085-XXX
Adjustable model
Adjustable model
fixed model
T
A
=25 : , 30ms pulse
F=120Hz, C
OUT
=25uF, Tantalum, Io=3A
GE1085-XXX
Io=10mA
Vin=Vout+3V
-
-
-
60
0.5
83
70
-
-
dB
%
: /W
Conditions
Io=10mA, T
J
=25 : , (Vin-Vout )=1.5V
Io=10mA, T
J
=25 : , 3.0V Vin 12V
Io=10mA, T
J
=25 : , 3.3V Vin 12V
Io=10mA, T
J
=25 : , 4.0V Vin 12V
Io=10mA, T
J
=25 : , 4.8V Vin 12V
Io=10mA, T
J
=25 : , 6.5V Vin 12V
Io=10mA, Vout+1.5<Vin<12
Vin=3.3V, 0mA<Io<3A, T
J
=25 :
Vin=3.0V, 0mA<Io<3A, T
J
=25 :
Vin=3.3V, 0mA<Io<3A, T
J
=25 :
Vin=4.0V, 0mA<Io<3A, T
J
=25 :
Vin=5.0V, 0mA<Io<3A, T
J
=25 :
Vin=8.0V, 0mA<Io<3A, T
J
=25 :
Io=3A( Vout=1% Vout)
Vin-Vout=5V
Vin=5V
Vin=12V, Io=10mA
Vin=12V, Io=0mA
(Note 1,2)
(Note 1,2)
(Note 1,2)
(Note 1,2)
(Note 1,2)
(Note 1,2)
MIN
1.225
1.470
1.764
2.450
3.235
4.900
-
-
-
-
-
-
-
-
3.1
-
-
-
-
TYP
1.250
1.500
1.800
2.500
3.300
5.000
-
-
12
15
20
26
40
1.3
-
5
55
-
0.008
MAX
1.275
1.530
1.836
2.550
3.365
5.100
0.2
1
15
18
25
33
50
1.4
-
10
100
12
0.04
UNIT
V
V
V
V
V
V
%
%
mV
mV
mV
mV
mV
V
A
mA
uA
mA
%/W
(No heat sink ;No air flow)
Control Circuitry/Power Transistor
-
0.65/2.7
-
: /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 in input and output and the output current. Guaranteed maximum power dissipation will not be available over the full
input/output range.
GE1085
Page: 2/4
ISSUED DATE :2005/06/01
REVISED DATE :2006/06/01B
Functional Description
Introduction
The GE1085 adjustable or fixed-mode Low Dropout (LDO) regulator is a 3 terminal device which can easily be
programmed by internal mask change to any voltage within the range of 1.25 to Vin-1.4V. The GE1085 only needs 1.4V
differential between Vin and Vout to maintain output regulation, in addition, 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 3A load step. The GE1085 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.
Load Regulation
Since the GE1085 is only a 3 terminal device, it is not possible to provide true remote sensing of the output voltage at the
load. But it can supply good load regulation by internal feedback bypass the external loss such as adjustable mode.
Stability
The GE1085 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 GE1085 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.
GE1085
Page: 3/4
ISSUED DATE :2005/06/01
REVISED DATE :2006/06/01B
Typical Performance Characteristics
3A
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
GE1085
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