ETL G5E1284-18 4a ultra low dropout positive adjustable or fixed-mode regulator Datasheet

ISSUED DATE :2005/05/24
REVISED DATE :2006/03/29B
G5E1284
4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
Description
The G5E1284 is 4A regulator with extremely low dropout voltage. This product is specifically designed to
provide well regulated supply for applications requiring 2.8V or lower voltages from 3.3V ATX power supplies
where high efficiency of the switch can be achieved without the cost and complexity associated with switching
regulator. One such application is the new graphic chipsets that requires anywhere from 2.4V to 2.7V supply.
Features
0.7V maximum dropout voltage at 4A load current
Built-in thermal shutdown
Output current limiting
Adjustable or fixed output voltage 1.5V,1.8V,2.5V,3.3V,5.0V
Fast transient response
Good noise rejection
Package Dimensions
REF.
A
b
c
D
E
L4
Typical Application
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
REF.
L5
c1
L
e
L1
Ø
Millimeter
Min.
Max.
6.20
6.60
1.25
1.45
13.25
14.25
1.70 REF.
2.60
2.89
3.71
3.96
Block Diagram
G5E1284-25
Pin Descriptions
Name
I/O
Adj (Gnd)
Description
A resistor divider from this pin to the Vout pin and ground sets the output voltage. (Gnd only for fixed mode)
Vsense
I
The pin is the positive side of the reference that allows remote load sensing to achieve excellent load
regulation. A minimum of 10uF capacitor must be connected from this pin to ground to insure stability.
Vin
I
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 higher than Vout in order for the device to regulate.
Vctrl
I
This pin is the supply pin for the internal control circuit as well as the base drive for the pass transistor. This
pin must always by higher than the Vout pin in order the device to regulate. A minimum of 100uF capacitor
must be connected from this pin to ground to insure stability.
Vout
O
The output of the regulator. A minimum of 100uF capacitor must be connected from this pin to ground to
insure stability.
G5E1284
Page: 1/4
ISSUED DATE :2005/05/24
REVISED DATE :2006/03/29B
Absolute Maximum Ratings
Ratings
Unit
Vin
Symbol
Input Voltage
Parameter
16
V
Vctrl
Control Input Voltage
18
V
PD
Power Dissipation (with heat sink or amount of copper board needed.)
2.4 ~ 4.4
W
TST
Storage Temperature Range
TOP
Operating Junction Temperature Range
-65 ~ + 150
0 ~ + 150
Electrical Characteristics Unless otherwise specified, these specifications apply over, Cin=1uF, Cout=10uF, TJ =0~150
Typical value refer to TJ =25
Parameter
Reference Voltage
. Vout=Vsense
Dropout Voltage
(Vin-Vout)
UNIT
1.275
V
, 2.2V Vin 12V, Vctrl=Vin+1V
1.470
1.500
1.530
V
, 2.5V Vin 12V, Vctrl=Vin+1V
1.764
1.800
1.836
V
, 3.2V Vin 12V, Vctrl=Vin+1V
2.450
2.500
2.550
V
, 4.0V Vin 12V, Vctrl=Vin+1V
3.235
3.300
3.365
V
, 5.7V Vin 12V, Vctrl=Vin+1V
4.900
5.000
5.100
V
-
-
0.2
%
-
-
1
%
G5E1284-15
Vin=3.0V, 0mA<Io<4A, TJ=25
, Vctrl=4V
-
12
15
mV
G5E1284-18
Vin=3.3V, 0mA<Io<4A, TJ=25
, Vctrl=4.3V
-
15
18
mV
G5E1284-25
Vin=4.0V, 0mA<Io<4A, TJ=25
, Vctrl=5V
-
20
25
mV
G5E1284-33
Vin=5.0V, 0mA<Io<4A, TJ=25
, Vctrl=6V
-
26
33
mV
G5E1284-50
Vin=8.0V, 0mA<Io<4A, TJ=25
, Vctrl=9V
-
40
50
mV
G5E1284-ADJ
Vadj=0V, for all conditions below. ( Vout=1%Vout)
Vin=2.05V, Io=1.5A
Vin=2.05V, Io=3.0A
Vin=2.05V, Io=4.0A
1.10
1.15
1.18
1.25
(fixed model)
Vin= Vout +0.8V, Io=4.0A ( Vout=1%Vout)
-
1.10
1.25
G5E1284-ADJ
Vadj=0V, for all conditions below. ( Vout=1%Vout)
Vctrl=2.75V, Io=1.5A
Vctrl=2.75V, Io=3.0A
Vctrl=2.75V, Io=4.0A
-
0.26
0.50
0.70
0.38
0.60
0.85
G5E1284-15
Vctrl=3.3V, Io=4.0A ( Vout=1%Vout)
-
0.70
0.85
V
4.2
-
-
A
G5E1284-50
Dropout Voltage
(Vctrl-Vout)
MAX
1.250
(Vin-Vout)=2V, 0mA<Io<4A, TJ=25
G5E1284-25
G5E1284-33
Load Regulation
TYP
1.225
G5E1284-XX
G5E1284-18
Line Regulator
MIN
, (Vin-Vout)=0.7V, Vctrl=Vin+1V
G5E1284-ADJ
G5E1284-15
Output Voltage
Conditions
Io=10mA, TJ =25
Io=10mA, TJ =25
Io=10mA, TJ =25
Io=10mA, TJ =25
Io=10mA, TJ =25
Io=10mA, TJ =25
Io=10mA, TJ =25
G5E1284-ADJ
.
, Vout+0.7<Vin<12, Vctrl=Vin+1V
, Vctrl=Vin+1V
V
V
V
G5E1284-18
G5E1284-25
G5E1284-33
Vctrl=Vout +1.5V, Io=4.0A ( Vout=1%Vout)
G5E1284-50
Current Limit
Vctrl=2.75V, Vin=2.05V, Vo=100mV, Vadj=0V
Minimum Load Current
Vctrl=5V, Vin=3.3V, Vadj=0V
-
5
10
mA
Thermal Regulation
30ms pulse
-
0.01
0.02
%/W
Ripple Rejection
Vctrl=5V, Vin=5V, Io=4.0A, Vadj=0V, TJ=25
60
70
-
dB
6
30
33
25
60
70
-
33
70
Control Pin Current
, Vripple=1Vpp at 120Hz
G5E1284-ADJ
Vadj=0V, for all conditions below.
Vctrl=2.75V, Vin=2.05V, Io=1.5A
Vctrl=2.75V, Vin=2.05V, Io=3.0A
Vctrl=2.75V, Vin=2.05V, Io=4.0A
G5E1284-15
Vctrl=3.3V, Vin=2.3V, Io=4.0A
-
mA
G5E1284-18
G5E1284-25
G5E1284-33
Vctrl= Vout +1.5V, Vin= Vout +0.8V, Io=4.0A
mA
G5E1284-50
Adjust Pin Current
Vctrl=2.75V, Vin=2.05V, Io=10mA, Vadj=0
-
50
150
uA
Quiescent Current
Vctrl=13V, Vin=12V, Io=10mA (fixed model)
-
-
12
mA
Thermal Resistance
Junction-to-Case
Control Circuitry/Power Transistor
-
2.5
-
/W
Note 1: G5E1284-ADJ incorporates an internal thermal shutdown that protects the device where the junction temperature exceeds the
allowable maximum junction temperature.
G5E1284
Page: 2/4
ISSUED DATE :2005/05/24
REVISED DATE :2006/03/29B
Functional Description
Introduction
The G5E1284 regulator is 5-terminal device designed specifically to provide extremely low dropout voltage comparable to
the PNP type without the disadvantage of the extra power dissipation due to the base current associated with PNP
regulators. This is done by bringing out the control pin of the regulator that provides the base current to the power NPN and
connecting it to a voltage that is greater than the voltage present at the Vin pin. This flexibility makes the G5E1284 ideal for
applications where dual inputs are available such as a computer motherboard with an ATX style power supply that provides
5V and 3.3V to the board. One such application is the new graphic chip sets that require anywhere from 2.4V to 2.7V
supply. The G5E1284 can easily be programmed with the addition of two external resistors to any voltages within the range
of 1.25V to 15.5V. Another major requirement of these graphic chips is the need to switch the load current from zero to
several amps in tens of nanoseconds at the processor pins, which translates to an approximately 300 to 500ns of current
step at the regulator. In addition, the output voltage tolerances are also extremely tight and they include the transient
response as part of the specification.
The G5E1284 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 number of output capacitors. Another feature of the device
is its true remote sensing capability that allows accurate voltage setting at the load rather than at the device.
Output Voltage Setting
The G5E1284 can be programmed to any voltage in the range of 1.25V to 15.5V with the addition of R1 and R2 external
resistors according to the following formula:
G5E1284-ADJ
The G5E1284-ADJ keeps a constant 1.25V between the Vsense pin and the Adj pin. By placing a resistor R1 across these
two pins and connecting the Vsense and Vout pin together, a constant current flows through R1, adding to the Iadj current
and into the R2 resistor producing a voltage equal to the (1.25/R1)*R2+Iadj*R2. This voltage is then added to the 1.25V to
set the output voltage. This is summarized in the above equation. Since the minimum load current requirement of the
G5E1284-adj is 10mA, R1 is typically selected to be 121 resistor so that it automatically satisfies this condition. 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.
Load Regulation
Since the G5E1284 has separate pins for the output (Vout) and the sense (Vsense), it is ideal for providing true remote
sensing of output voltage at the load. This means that the voltage drops due to parasitic resistance such PCB traces
between the regulator and the load are compensated for using remote sensing. Figure following shows a typical application
of the G5E1284-ADJ with remote sensing.
G5E1284-ADJ
Stability
The G5E1284-XX requires the use of an output capacitor as part of the frequency compensation in order to make the
regulator stable. Typical designs for the microprocessor application use standard electrolytic with typical ESR in the range
of 50 to 100m and an output capacitance of 100uF to 1000uF. Fortunately as the capacitance increases, the ESR
decreases resulting in a fixed RC time constant. The G5E1284-XX takes advantage of the phenomena in making the
overall regulator loop stable. For most applications a minimum of 100uF aluminum electrolytic capacitor insures both
stability and good transient response.
Thermal Design
The G5E1284-XX incorporates an internal thermal 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 this number.
G5E1284
Page: 3/4
ISSUED DATE :2005/05/24
REVISED DATE :2006/03/29B
Performance Characteristics
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
G5E1284
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