A-POWER APU1160

Technology Licensed from International Rectifier
APU1160
6A ULTRA LOW DROPOUT POSITIVE
ADJUSTABLE REGULATOR
DESCRIPTION
FEATURES
0.62V Dropout at 6A
Fast Transient Response
1% Voltage Reference Initial Accuracy
Built-In Thermal Shutdown
RoHS Compliant
The APU1160 is a 6A regulator with extremely low dropout voltage using a proprietary bipolar process that
achieves comparable equivalent on resistance to that of
discrete MOSFETs. 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 a switcher can be achieved without the cost and complexity associated with switching
regulators.
APPLICATIONS
VGA Card Applications
On-Board Low Voltage Regulator Supply such
as 3.3V to 2.8V
TYPICAL APPLICATION
3.3V
C1
100uF
APU1160
VIN
5
VCTRL
4
VOUT
3
Adj
VSENSE
2.7V
R1
100
1%
2
R2
124
1%
1
5V
C3
100uF
C2
100uF
Figure 1 - Typical application of APU1160 in a 3.3V to 2.8V.
PACKAGE ORDER INFORMATION
TJ (°C)
5-PIN PLASTIC
TO-263 (S)
0 To 125
APU1160S
Data and specifications subject to change without notice.
200428061-1/5
APU1160
ABSOLUTE MAXIMUM RATINGS
Input Voltage (V IN) ....................................................
Control Input Voltage (V CTRL) .....................................
Power Dissipation .....................................................
Storage Temperature Range ......................................
Operating Junction Temperature Range .....................
7V
14V
Internally Limited
-65°C To 150°C
0°C To 150°C
PACKAGE INFORMATION
5-PIN PLASTIC TO-263 (S)
FRONT VIEW
Tab is
V OUT
5
VIN
4
VCTRL
3
VOUT
2
Adj
1
VSENSE
θJA=35°C/W for 0.5" square pad
ELECTRICAL SPECIFICATIONS
Unless otherwise specified, these specifications apply over CIN=mF, COUT=10mF, and TJ=0 to 1258C.
Typical values refer to TJ=258C. VOUT=VSENSE.
PARAMETER
Reference Voltage
SYM
VREF
TEST CONDITION
VCTRL=2.75, VIN=2V, Io=10mA,
TJ=258C, V ADJ=0V
MIN
TYP
MAX
UNITS
1.225
1.250
1.275
V
1.225
1.250
1.275
VCTRL=2.7 to 12V, VIN=2.05V to 5.5V,
Io=10mA to 6A, VADJ=0V
Line Regulation
Load Regulation (Note 1)
Dropout Voltage (Note 2)
(V CTRL - VOUT)
Dropout Voltage (Note 2)
(V IN - VOUT)
Current Limit
Minimum Load Current (Note 3)
Thermal Regulation
Ripple Rejection
VCTRL=2.5V to 7V, VIN=1.75V to 5.5V,
Io=10mA, V ADJ=0V
VCTRL=2.75V, VIN=2.1V,
Io=10mA to 6A, VADJ=0V
VADJ=0V for all conditions below:
VIN=2.05V, Io=1.5A
VIN=2.05V, Io=5A
VIN=2.05V, Io=6A
VADJ=0V for all conditions below:
VCTRL=2.75V, Io=1.5A
VCTRL=2.75V, Io=5A
VCTRL=2.75V, Io=6A
VCTRL=2.75V, VIN=2.05V,
DVo=100mV, V ADJ=0V
VCTRL=5V, VIN=3.3V, V ADJ=0V
30ms Pulse
VCTRL=5V, VIN=5V, Io=5A, VADJ=0V,
TJ=258C, VRIPPLE=1V PP at 120Hz
3
mV
6
mV
1.00
1.10
1.20
V
1.30
0.15
0.40
0.55
0.20
0.52
0.62
5
0.01
10
0.02
6.2
60
70
V
A
mA
%/W
dB
2/5
APU1160
PARAMETER
Control Pin Current
SYM
Adjust Pin Current
IADJ
TEST CONDITION
VADJ=0V for all below conditions:
VCTRL=2.75V, VIN=2.05V, Io=1.5A
VCTRL=2.75V, VIN=2.05V, Io=5A
VCTRL=2.75V, VIN=2.05V, Io=6A
VCTRL=2.75V, VIN=2.05V, V ADJ=0V
Note 1: Low duty cycle pulse testing with Kelvin connections are required in order to maintain accurate data.
Note 2: Dropout voltage is defined as the minimum differential between V IN and V OUT required to maintain regulation at VOUT. It is measured when the output voltage
drops 1% below its nominal value.
MIN
TYP
15
50
60
50
MAX
UNITS
mA
120
mA
Note 3: Minimum load current is defined as the minimum current required at the output in order for the output voltage to maintain regulation. Typically the resistor
dividers are selected such that it automatically maintains this current.
PIN DESCRIPTIONS
PIN # PIN SYMBOL
1
VSENSE
2
3
Adj
VOUT
4
VCTRL
5
VIN
PIN DESCRIPTION
This pin is the positive side of the reference which allows remote load sensing to achieve
excellent load regulation.
A resistor divider from this pin to the VOUT pin and ground sets the output voltage.
The output of the regulator. A minimum of 10mF capacitor must be connected from this
pin to ground to insure stability.
This pin is the supply pin for the internal control circuitry as well as the base drive for the
pass transistor. This pin must always be higher than the V OUT pin in order for the device to
regulate. (See specifications)
The input pin of the 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. (See specifications)
BLOCK DIAGRAM
V IN 5
3 VOUT
V CTRL 4
1 VSENSE
+
1.25V
+
CURRENT
LIMIT
THERMAL
SHUTDOWN
2 Adj
Figure 2 - Simplified block diagram of the APU1160.
3/5
APU1160
APPLICATION INFORMATION
Introduction
The APU1160 adjustable regulator is a five-terminal device designed specifically to provide extremely low dropout voltages 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 grater than the voltage present
at the VIN pin. This flexibility makes the APU1160 ideal
for applications where dual inputs are available such as
a computer mother board 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 such as the Intel I740
chip set. The APU1160 can easily be programmed with
the addition of two external resistors to any voltages
within the range of 1.25 to 5.5 V. Another major requirement of these graphic chips such as the Intel I740 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 APU1160 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
which allows accurate voltage setting at the load rather
than at the device.
Output Voltage Setting
The APU1160 can be programmed to any voltages in the
range of 1.25V to 5.5V with the addition of R1 and R2
external resistors according to the following formula:
(
VOUT = VREF3 1+
R2
R1
) +I
VIN
APU1160
VCTRL
VCTRL
V SENSE
Adj
V REF
IADJ = 50uA
R1
R2
Figure 3 - Typical application of the APU1160
for programming the output voltage.
The APU1160 keeps a constant 1.25V between the V SENSE
pin and the VADJ 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)3R2 + IADJ3R2. 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 APU1160 is
10mA, R1 is typically selected to be a 121V resistor so
that it automatically satisfies this condition. Notice that
since the IADJ is typically in the range of 50mA, it adds a
small error to the output voltage and should be considered when very precise output voltage setting is required.
Load Regulation
Since the APU1160 has separate pins for the output (V OUT )
and the sense (V SENSE), it is ideal for providing true remote sensing of the output voltage at the load. This
means that the voltage drops due to parasitic resistance
such as PCB traces between the regulator and the load
are compensated for using remote sensing. Figure 4
shows a typical application of the APU1160 with remote
sensing.
VI N
V IN
V OUT
APU1160
3R2
ADJ
VC T R L
Where:
VREF = 1.25V Typically
IADJ = 50mA Typically
R1 & R2 as shown in Figure 3:
VOUT
V OUT
V IN
V SENSE
V CTRL
RL
Adj
R1
R2
Figure 4 - Schematic showing connection
for best load regulation.
4/5
APU1160
Stability
The APU1160 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 applications use standard electrolytic capacitors with
typical ESR in the range of 50 to 100mV and an output
capacitance of 500 to 1000mF. Fortunately as the capacitance increases, the ESR decreases resulting in a
fixed RC time constant. The APU1160 takes advantage
of this phenomena in making the overall regulator loop
stable.
For most applications a minimum of 100mF aluminum
electrolytic capacitor such as Sanyo, MVGX series,
Panasonic FA series as well as the Nichicon PL series
insures both stability and good transient response.
Thermal Design
The APU1160 incorporates an internal thermal shutdown
that protects the device when the junction temperature
exceeds the allowable maximum junction temperature.
Although this device can operate with junction temperatures in the range of 1508C, 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. The example below
shows the steps in selecting the proper surface mount
package.
Assuming, the following conditions:
VOUT = 2.8V
VIN = 3.3V
VCTRL = 5V
IOUT = 3A (DC Avg)
Calculate the maximum power dissipation using the following equation:
( I60 )3(V - V )
3
= 13(3.3 - 2.8)+( ) 3(5 - 2.8) = 1.61W
60
PD = IOUT3(V IN - VOUT)+
PD
OUT
CTRL
OUT
Using table below select the proper package and the
amount of copper board needed.
Pkg
TO-263
TO-263
TO-263
TO-263
Copper
θJA(°C/W)
Area
1.4"X1.4"
25
1.0"X1.0"
30
0.7"X0.7"
35
Pad Size
45
Max Pd
(TA=25°C)
4.4W
3.7W
3.1W
2.4W
Max Pd
(TA=45°C)
3.6W
3.0W
2.6W
2.0W
Note: Above table is based on the maximum junction
temperature of 1358C.
5/5