Ver: 1.2
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
1
G1085
Global Mixed-mode Technology Inc.
3A 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 3A
Applications
Post Regulation for Switching DC/DC Con-
verter
High Efficiency Linear Regulator
Battery Charger
Battery Powered Instrumentation
Motherboard
General Description
The G1085 is a low dropout linear regulator with a
dropout of 1.2V at 3A 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 G1085 provides over temperature and over
current protection circuits to prevent it from being
damaged by abnormal operating conditions.
The G1085 is available in TO-252 package and
TO- 263 packages. A minimum of 100F tantalum
electrolytic capacitor is required at the output to
improve the transient response and stability.
Ordering Information
PIN OPTION
ORDER
NUMBER
ORDER NUMBER
(Pb free)
MARKING
TEMP.
RANGE
PACKAGE
1 2 3
G1085T43U G1085T43Uf
G1085
-40C to +85C
TO-252
GND/ADJ
V
OUT
V
IN
G1085T53U G1085T53Uf
G1085
-40C to +85C
TO-263
GND/ADJ
V
OUT
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
PIN OPTION
PACKING
T4: TO-252
1
2
3
U & D: Tape & Reel Direction
T5: TO-263
3: GND/ADJ
V
OUT
V
IN
T:
Tube
Package Type Typical Application
[Note 4]: Type of C
OUT
V
IN
G1085
C1
100F
V
OUT
I
O
C
OUT
100F
R2
R1
GND/ADJ
V
IN
V
OUT
Top View
1
2
3
TO-252TO-263
V
IN
G1085
C1
100F
V
OUT
I
O
C
OUT
100F
R2
R1
GND/ADJ
V
IN
V
OUT
V
IN
G1085
C1
100F
V
OUT
I
O
C
OUT
100F
R2
R1
GND/ADJ
V
IN
V
OUT
Top View
1
2
3
TO-252TO-263
Top View
1
2
3
TO-252TO-263
Ver: 1.2
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
2
G1085
Global Mixed-mode Technology Inc.
Absolute Maximum Ratings
(Note 1)
Input Voltage....................................................7V
Power Dissipation Internally Limited (Note 2)
Maximum Junction Temperature.........................150C
Storage Temperature Range........-65C
T
J
+150C
Reflow Temperature (soldering, 10sec)............260C
Thermal Resistance Junction to Ambient
TO-252
(1)
.................................................125C/W
TO-263
(1)
.................................................100C/W
Thermal Resistance Junction to Case
TO-252......................................................10C/W
TO-263.......................................................6C/W
ESD Rating (Human Body Model)............................2kV
Note
(1)
: See Recommended Minimum Footprint
Operating Conditions
(Note 1)
(V
IN
-V
ADJ
) Voltage.....................................2.5V~5.5V
Temperature Range.........................-40C
T
A
85C
Electrical Characteristics
Operating Conditions: V
IN
7V, T
A
=T
J
= 25C unless otherwise specified. [Note3]
PARAMETER CONDITION
MIN
TYP
MAX
UNIT
Reference Voltage
V
IN
- V
OUT
= 2V, I
OUT
= 10mA
1.225
1.250
1.275
V
Line Regulation
(V
OUT
+ 1.5V) < V
IN
< 7V, I
OUT
= 10mA
---
0.5
1
%
Load Regulation
(V
IN
- V
OUT
) = 2V, 10mA < I
OUT
<3A ---
0.04
0.5
%
Dropout Voltage
V
OUT
= 2%, I
OUT
= 3A
--- 1.3 1.4 V
Current Limit
(V
IN
- V
OUT
) = 2V
---
5.4
---
A
Adjust Pin Current Change
V
IN
- V
OUT
= 2V, 10mA < I
OUT
<
3A
--- 0.15 --- A
Minimum Load Current
1.5V < (V
IN
- V
OUT
) < 5.25V
10
---
---
mA
Quiescent Current
V
IN
- V
OUT
= 2V
---
80
150
A
Ripple Rejection
f = 120Hz, C
OUT
= 10F Tantalum,
(V
IN
- V
OUT
) = 3V, I
OUT
= 1A
--- 48 --- dB
Temperature Stability
V
IN
= 4V, I
O
=10mA ---
0.3
---
%
RMS Output Noise (% of V
OUT
) T
A
= 25C, 10Hz < f < 10kHz, I
LOAD
= 10mA
---
0.007
---
%
Thermal Shutdown
Junction Temperature
---
150
---
C
Thermal
Shutdown
Hysteresis
--- 30 --- C
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Con-
ditions are conditions under which the device functions but the specifications might not be guaranteed. For
guaranteed specifications and test conditions see the Electrical Characteristics.
Note 2: The maximum power dissipation is a function of the maximum junction temperature, T
Jmax
; total thermal re-
sistance,
JA
, and ambient temperature T
A
. The maximum allowable power dissipation at any ambient tem-
perature is T
jmax
-T
A
/
JA
. If this dissipation is exceeded, the die temperature will rise above 150C and IC
will go into thermal shutdown.
Note3: Low duty pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
Note4: The type of output capacitor should be tantalum or aluminum.
Ver: 1.2
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
3
G1085
Global Mixed-mode Technology Inc.
Definitions
Output Voltage
The G1085 provides an adjustable output voltage from
1.25V to 5V. with two external resistors. It can be for-
mulated as:
R
2
V
OUT
= 1.25V x
(
1+
R
1
)
+ I
ADJ
x R
2
I
ADJ
= 80A (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.
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: 1.2
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
4
G1085
Global Mixed-mode Technology Inc.
Typical Performance Characteristics
(V
IN
-V
OUT
=3V, V
OUT
=1.25V, C
IN
=100F, C
OUT
=100F, T
A
=25C, unless otherwise noted.)
0
10
20
30
40
50
60
70
10
100
1000
10000
100000
1000000
Frequency(Hz)
R
i
pple Reject
ion
(
d
B)
I
L
=100mA
1.225
1.235
1.245
1.255
1.265
1.275
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
V
IN
(V)
V
OUT
(V)
Line Transient Response
Load Transient Response
Output Noise
Short Circuit-Current
Ripple Rejection
Line Regulation
I
L
=10mA
T=25C
T=25C
T=75C
100mA
(V
IN
-V
OUT
)>V
dropout
V
ripple
<0.5 V
P-P
C
OUT
=220F
3A
2A
1A
Ver: 1.2
Sep 20, 2004
TEL: 886-3-5788833
http://www.gmt.com.tw
5
G1085
Global Mixed-mode Technology Inc.
Typical Performance Characteristics
(continued)
Dropout Voltage vs. I
OUT
Load Regulation
Output Voltage vs. Temperature
I
L
= 2.5A
Adj Pin Current vs. Temperature
0
0.5
1
1.5
2
0
1
2
3
4
I
OUT
(A)
Drop
out V
o
lt
age (V
)
T = 25C
1.240
1.243
1.245
1.248
1.250
1.253
1.255
-50
-30
-10
10
30
50
70
Temperature (C)
V
OU
T
(V
)
V
IN
= 5V
V
IN
= 3V
30
40
50
60
70
80
90
100
-50
-30
-10
10
30
50
70
Temperature (C)
A
d
j Pin C
u
rrent
(A)
V
IN
= 5V
V
IN
= 3V
-5
-3
-1
1
3
5
-50
-30
-10
10
30
50
70
Temperature (C)
Out
put V
o
lt
age Devi
ation
(mV
)
I
L
= 10mA~2.5A
V
IN
= 3V
V
IN
= 5V
I
L
= 2.5A
0
0.5
1
1.5
2
2.5
3
3.5
4
0
1
2
3
4
5
PCB Top Copper Area (in
2
)
Max
.
Di
ssi
pati
on
P
o
w
e
r (W
)
G1085T43(TO-252) Max. Power
Dissipation vs. PCB Top Copper
Area T
AMB
= 25C ; Still Air
0
0.5
1
1.5
2
2.5
3
3.5
4
25
35
45
55
65
75
85
T
AMB
(C)
M
a
x. D
i
ss
ipat
ion
Pow
e
r (W)
A=0.1
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
G1085T43(TO-252) Max. Power
Dissipation vs. T
AMB
(still air)
( Different PCB Top Copper Area )
Unit : in
2
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