Global Mixed-mode Technology Inc.
G1084
5A Adjustable Low-Dropout Linear Regulator
Features
Available in Adjust Version
Space Saving TO-252 Package and TO-263
Package
Internal Short Circuit Current Limiting
Internal Over Temperature Protection
Output Current 5A
General Description
The G1084 is a low dropout linear regulator with a
dropout of 1.2V at 5A of load current. It is avail-
able in an adjustable version, which can set the
output from 1.25V to 5V with only two external
resistors.
The G1084 provides over temperature and over
current protection circuits to prevent it from being
damaged by abnormal operating conditions.
The G1084 is available in TO-252 and TO-263
packages. A minimum of 220µF tantalum electro-
lytic capacitor is required at the output to improve
the transient response and stability.
Applications
Post Regulation for Switching DC/DC Con-
verter
High Efficiency Linear Regulator
Battery Charger
Battery Powered Instrumentation
Motherboard
Ordering Information
ORDER
NUMBER
G1084T43U
G1084T53U
ORDER NUMBER
MARKING TEMP. RANGE
(Pb free)
G1084T43Uf
G1084T53Uf
G1084
G1084
-40°C to +85°C
-40°C to +85°C
PACKAGE
TO-252
TO-263
1
GND/ADJ
GND/ADJ
PIN OPTION
2
3
V
OUT
V
OUT
V
IN
V
IN
* For other package types and pin options, please contact us at sales
@
gmt.com.tw
Order Number Identification
GXXXX
XX
X
X
Packing Type
Pin Option
Package Type
Part Number
PACKAGE TYPE
T4: TO-252
T5: TO-263
PIN OPTION
1
3: GND/ADJ
2
V
OUT
3
V
IN
PACKING
U: Tape & Reel
Package Type
Typical Application
[Note 4]: Type of C
OUT
I
O
V
IN
V
IN
G1084
V
OUT
GND/ADJ
V
OUT
Top View
C1
220µF
R1
R2
C
OUT
220µF
1
2
3
TO-252、TO-263
Ver: 1.1
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
1
Global Mixed-mode Technology Inc.
Definitions
Output Voltage
The G1084 provides an adjustable output voltage from
1.25V to 5V. with two external resistors. It can be for-
mulated as:
V
OUT
= 1.25V x
(
1+
I
ADJ
= 80µA (typ.)
Dropout Voltage
The input/output Voltage differential at which the
regulator output no longer maintains regulation against
further reductions in input voltage. Measured when the
output drops 2% below its nominal value. Dropout
voltage is affected by junction temperature, load cur-
rent and minimum input supply requirements.
R
2
R
1
G1084
)
+ I
ADJ
x R
2
Line Regulation
The change in output voltage for a change in input
voltage. The measurement is made under conditions
of low dissipation or by using pulse techniques such
that average chip temperature is not significantly af-
fected.
Load Regulation
The change in output voltage for a change in load
current at constant chip temperature. The measure-
ment is made under conditions of low dissipation or by
using pulse techniques such that average chip tem-
perature is not significantly affected.
Maximum Power Dissipation
The maximum total device dissipation for which the
regulator will operate within specifications.
Quiescent Bias Current
Current which is used to operate the regulator chip
and is not delivered to the load.
Ver: 1.1
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
3
Global Mixed-mode Technology Inc.
Typical Performance Characteristics
(V
IN
-V
OUT
= 3V, V
OUT
= 1.25V, C
IN
= 220µF, C
OUT
= 220µF, T
A
=25°C, unless otherwise noted.)
G1084
Load Transient Response
Line Transient Response
Short Circuit-Current
Output Noise
Ripple Rejection
70
60
1.275
1.270
1.265
Line Regulation
Ripple Rejection (dB)
50
625mA
40
30
20
10
0
10
100
1000
10000
100000
1000000
1.260
1A
V
OUT
(V)
1.255
1.250
1.245
1.240
1.235
1.230
1.225
2.5
3
T = 25°C
T = -25°C
(V
IN
-V
OUT
)>V
dropout
V
ripple
<0.5V
P-P
C
OUT
= 220µF
3.5
4
4.5
5
5.5
6
Frequency (Hz)
V
IN
(V)
Ver: 1.1
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
4
Global Mixed-mode Technology Inc.
Typical Performance Characteristics
(continued)
Dropout Voltage vs. I
OUT
2
G1084
Load Regulation
5
T = 25°C
Output Voltage Deviation (mV)
3
I
L
= 10mA~2.5A
Dropout Voltage (V)
1.5
1
V
IN
= 3V
-1
V
IN
= 5V
1
0.5
-3
0
0
1
2
-5
I
OUT
(A)
3
4
-50
-30
-10
10
30
50
70
Temperature (°C)
Output Voltage vs. Temperature
1.255
Adj Pin Current vs. Temperature
100
90
1.253
V
IN
= 5V
Adj Pin Current (µA)
1.250
80
70
60
50
40
30
V
IN
= 3V
V
IN
= 5V
V
OUT
(V)
1.248
V
IN
= 3V
1.245
1.243
I
L
= 2.5A = 2.5A
I
L
1.240
-50
-30
-10
10
30
50
70
-50
-30
-10
10
30
50
70
Temperature (°C)
Temperature (°C)
G1084T43(TO-252) Max. Power
Dissipation vs. PCB Top Copper
Area T
AMB
= 25°C ; Still Air
4
3.5
4
3.5
3
2.5
2
1.5
1
0.5
0
G1084T43(TO-252) Max. Power
Dissipation vs. T
AMB
(still air)
( Different PCB Top Copper Area )
Unit : in
2
A=0.1
Max. Dissipation Power (W)
Max. Dissipation Power (W)
A=0.2
A=0.3
A=0.4
A=0.5
A=1.0
A=1.5
A=2.0
A=2.5
A=3.0
A=3.5
A=4.0
A=4.5
A=5.0
3
2.5
2
1.5
1
0.5
0
0
1
2
3
2
4
5
25
35
45
55
65
75
85
PCB Top Copper Area (in )
T
AMB
(°C)
Ver: 1.1
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
5
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