®
P
5
A
SPX29501/02
Rev.
B
5A Low Dropout Voltage Regulator
November 2008
FEATURES
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Adjustable Output Down to 1.25V
1% Output Accuracy
Output Current of 5A
Low Dropout Voltage:
420mV
@ 5A
Tight Line Regulation: 0.06%
Load Regulation: 0.2%
Fast Transient Response
Reverse-Battery Protection
Current Limit and Thermal Protection
Powering VGA & Sound Card
Power PC™ Supplies
SMPS Post Regulator
High Efficiency “Green” Computer
Systems
High Efficiency Linear Power Supplies
Constant Current Regulators
Adjustable Power Supplies
Battery Charger
SPX29502
5 Pin TO-263
SP29500
3 Pin TO-220
1
2
3
1
2
3
APPLICATIONS
INPUT
OUTPUT
ADJUST
GND
EN
V
IN
GND V
OUT
Now Available in Lead Free Packaging
DESCRIPTION
The SPX29501/02 are 5A highly accurate voltage regulators with a low dropout voltage of
420mV
@ 5A. These regulators are specifically designed for low voltage applications that require a low dropout
voltage and a fast transient response. They are fully fault protected against over-current, reverse
battery, and positive and negative voltage transients. On-Chip trimming adjusts the reference voltage
to 1% initial accuracy. Other features include Enable, and Error Flag.
The SPX295001/02 are offered in 5-pin TO-220 & TO-263 packages. For a 1.5A version, refer
to the SPX29150 data sheet. For a 3A version, refer to the SPX29300 datasheet.
TYPICAL APPLICATION CIRCUITS
1
SPX29502
+
2
GND
3
5
ADJ
4
+
R1
V
IN
6.8µF
+
1
SPX29500
3
2
+
22µF
V
OUT
V
IN
6.8µF
V
OUT
22µF
R2
Figure 1. Fixed Output Linear Regulator
Exar Corporation
48720 Kato Road, Fremont CA 94538, USA
Figure 2. Adjustable Output Linear Regulator
www.exar.com
Tel. +1 510 668-7000 – Fax. +1 510 668-7001
ABSOLUTE MAXIMUM RATINGS
Lead Temperature (soldering, 5 seconds) ................260°C
Storage Temperature Range........................-65°C to +150°C
Operating Junction Temperature Range......-40°C to +125°C
Input Voltage (Note 1) .................................................... 20V
OPERATING RATINGS
Input Voltage ................................................................... 16V
ELECTRICAL CHARACTERISTICS
Specifications are at V
IN
= V
OUT
+ 1V and I
OUT
= 10mA, C
IN
= 6.8µF, C
OUT
= 22µF, T
A
= 25°C, unless otherwise specified.
The
♦
denotes the specifications which apply over the full operating temperature range, unless otherwise specified.
PARAMETER
Fixed Voltage Options
1.8V Version
Output Voltage
2.5V Version
Output Voltage
3.3V Version
Output Voltage
5.0V Version
Output Voltage
All Voltage Options
Line Regulation
Load Regulation
∆V/∆T
Dropout Voltage, except
1.8V
Ground Current
(Note 4)
Ground Pin Current
at Dropout
Current Limit
Output Noise Voltage
(10Hz to 100kHz)
I
L
=100mA
Reference Voltage
Reference Voltage
Adjust Pin Bias Current
Reference Voltage
Temp. Coeff.
Adjust Pin Bias
Current Temp. Coeff.
1.228
1.215
1.203
40
20
0.1
4.950
4.900
5.000
5.000
0.06
0.2
20
90
250
420
20
70
3
7.5
425
350
1.240
1.252
1.265
1.277
80
120
V
♦
V
nA
♦
ppm/°C
nA/°C
(Note 6)
Adjustable version only (Note 7)
10
5.050
5.100
0.5
1
100
250
800
50
mA
mA
A
µV
RMS
V
I
OUT
= 10mA
♦
10mA
≤
I
OUT
≤
5A, 6.0V
≤
V
IN
≤
16V
I
OUT
=10mA,(V
OUT
+1V)
≤
V
IN
≤
16V
V
IN
=V
OUT
+2V, 10mA≤ I
OUT
≤
I
FL
(Note 2)
♦
V
OUT
Temp Coefficient (Note 5)
♦
I
OUT
=250mA
eg I
OUT
=2.5A
♦
I
OUT
=5A
♦
I
OUT
=2.5A
I
OUT
=5A
V
IN
=0.5V less than specified V
OUT,
I
OUT
=10mA
♦
(Note 3)
C
L
=22µF
C
L
=33µF
Adjustable version only
3.267
3.234
3.300
3.300
3.333
3.366
V
I
OUT
= 10mA
♦
10mA
≤
I
OUT
≤
5A, 4.3V
≤
V
IN
≤
16V
2.475
2.450
2.500
2.500
2.525
2.550
V
I
OUT
= 10mA
♦
10mA
≤
I
OUT
≤
5A, 3.5V
≤
V
IN
≤
16V
1.782
1.764
1.800
1.800
1.818
1.836
V
I
OUT
= 10mA
♦
10mA
≤
I
OUT
≤
5A, 2.8V
≤
V
IN
≤
16V
MIN
TYP
SPX29501
MAX
UNITS
CONDITIONS
SPX29501/02
%
%
ppm/°C
mV
Rev:B
Nov 2008
SPX29500/01/02/03 5A Low Dropout Voltage Regulator
©
Copyright 2008
Exar
Corporation
2
ELECTRICAL CHARACTERISTICS: Continued
Specifications are at V
IN
= V
OUT
+ 1V and I
OUT
= 10mA, C
IN
= 6.8µF, C
OUT
= 22µF, T
A
= 25°C, unless otherwise specified.
The
♦
denotes the specifications which apply over the full operating temperature range, unless otherwise specified.
PARAMETER
Flag Output
(Error Comparator)
Output Leakage
Current
Output Low Voltage
Upper Threshold
Voltage
Lower Threshold
Voltage
Hysteresis
Enable Input
Input Logic Voltage
Low (OFF)
High (ON)
ENABLE Input Current
40
25
MIN
TYP
SPX29501
0.01
220
60
75
15
SPX29501/02
0.8
2.4
100
0.6
Regulator Output
Current in Shutdown
Thermal Resistance
10
500
2
60
2
60
°C/W
600
750
2
4
µA
♦
µA
♦
µA
♦
TO-220 Junction to Case, at Tab
TO-220 Junction to Ambient
TO-263 Junction to Case, at Tab
TO-263 Junction to Ambient
(Note 9)
V
EN
=0.8V
V
EN
=16V
V
(Note 10)
95
140
1
2
300
400
µA
♦
mV
♦
mV
♦
mV
♦
mV
Device set for 5V, (Note 8)
Device set for 5V, (Note 8)
Device set for 5V, (Note 8)
Device set for 5V,V
IN
=4.5V, I
OL
=250µA
V
OH
=16V
MAX
UNITS
CONDITIONS
NOTES:
Note 1:
Maximum positive supply voltage of 20V must be of limited duration (<100ms) and duty cycle of less than 1%. The
maximum continuous supply voltage is 16V.
Note 2:
Full load current (I
FL
) is defined as 5A.
Note 3:
V
IN
= V
OUT (NOMINAL)
+1V. For example, use V
IN
= 4.3V for a 3.3V regulator. Employ pulse-testing procedures to minimize
temperature rise.
Note 4
Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current
plus the ground pin current.
Note 5:
Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 6:
Thermal regulation is defined as the change in output voltage at time T after a change in power dissipation is applied,
excluding load / line regulation effects. Specifications for a 200mA load pulse as V
IN
= 20V (a 4W pulse) for t = 10ms.
Note 7:
V
REF
≤
V
OUT
≤
(V
IN
-1), 2.3V≤V
IN
≤
16V, 10mA
≤
I
L
≤
I
FL
, T
j
< T
jmax
.
Note 8:
Comparator threshold is expressed in terms of a voltage differential at the Adjust terminal below the nominal reference
voltage measured 6V input. To express these thresholds in terms of output voltage change, multiply the error amplifier gain =
V
OUT
/V
REF
= (R1 + R2)/R2. For example, at a programmable output voltage of 5V, the Error output is guaranteed to go low when
the output drops by 95mVx 5V/ 1.240V = 383mV. Threshold remain constant as a percent of V
OUT
as V
OUT
is varied, with the
dropout warning occurring at typically 5% below nominal, 7.7% guaranteed.
Note 9:
V
EN
≤
0.4V and V
IN
≤
16V, V
OUT
= 0.
Note 10:
Measured with I
OUT
= I
OUT
MIN (10mA).
Rev:B
Nov 2008
SPX29500/01/02/03 5A Low Dropout Voltage Regulator
©
Copyright 2008
Exar
Corporation
3
FUNCTIONAL DIAGRAM
IN
O.V
I
LIMIT
FLAG
+
-
1.180V
Reference
1.240V
+
-
ADJ
EN
Thermal
Shutdown
20V
R1*
OUT
R2*
GND
TYPICAL PERFORMANCE CHARACTERISTICS
600
120
110
100
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
5
Output Current (A)
550
500
Ground Current (mA)
Dropout (mA)
450
400
350
300
250
200
150
100
50
0
1
2
3
4
5
6
Output Current (A)
Figure 3. Ground Current (mA) vs. Output Current (A)
Figure 4. Dropout (mV) vs. Output Current (A)
V
OUT
(AC)
V
OUT
(AC)
I
OUT
(2A/DIV)
V
IN
Figure 5. Load Transient (V
IN
=4V, V
O
=3.3V, C
OUT
=22µF,
10mA~5A)
Rev:B
Nov 2008
Figure 6. Line Transient (C
OUT
=22µF, I
O
=10mA)
SPX29500/01/02/03 5A Low Dropout Voltage Regulator
©
Copyright 2008
Exar
Corporation
4
APPLICATION INFORMATION
The SPX29501/02 incorporates protection
against over-current faults, reversed load
insertion, over temperature operation, and
positive
and negative transient voltage.
Thermal Considerations
load transient response is needed. If the power
source has a high AC impedance, a 0.1µF ce-
ramic capacitor between input & ground is rec-
ommended.
Minimum Load Current
Although the SPX29501/02 offers limiting
circuitry for overload conditions, it is still
necessary to insure that the maximum junction
temperature is not exceeded in the application.
Heat will flow through the lowest resistance
path, the junction-to-case path. In order to insure
the best thermal flow of the component, proper
mounting is required.
TO-220 Design Example:
To ensure a proper behavior of the regulator
under light load, a minimum load of 10mA for
SPX29501/02 is required.
Adjustable Regulator Design
The SPX29502
is an
adjustable regulator that
can be programmed to any value between 1.24V
and 16V using 2 resistors, R1 and R2. The
relationship between the resistors is:
R1 = R2(V
OUT
/1.24-1).
Error Flag
Assume that V
IN
= 8V, V
OUT
= 5V, I
OUT
= 5A, T
A
= 50°C,
θ
HA
= 1°C/W,
θ
CH
= 2°C/W, and
θ
JC
=
2°C/W, where:
T
A
= ambient temperature,
θ
HA
= heatsink to ambient thermal
resistance
θ
CH
= case to heatsink thermal
resistance
θ
JC
= junction to case thermal
resistance
The power calculated under these conditions is:
P
D
= (V
IN
– V
OUT
) * I
OUT
= 15W.
And the junction temperature is calculated as
T
J
= T
A
+ P
D
* (θ
HA
+
θ
CH
+
θ
JC
) or
T
J
= 50 + 15 * (1+2+2) = 125°C
Reliable operation is insured.
Capacitor Requirements
The SPX29501 features an error flag that
indicates either an over current or under voltage
condition. The flag output goes low, sinking
10mA when either condition occurs.
Enable Input
The SPX29501/02 have an Enable function that
switches the regulator on and off. Their thresh-
olds are TTL compatible. Enabling the regulator
requires approximately 20µA of current.
Typical Application Circuits
Figure 1 represents at typical fixed output regu-
lator. Figure 2 represents an adjustable output
regulator. The values of R1 and R2 set the output
voltage value as follows:
V
OUT
=V
REF
* [1 + (R1/R2)].
For best results, the total series resistance should
guarantee a minimum regulator load current of
10mA.
The output capacitor is needed to insure stability
and minimize the output noise. The value of the
capacitor varies with the load. However, a
minimum value of 22µF aluminum capacitor
will guarantee stability over all load conditions.
A tantalum capacitor is recommended if a faster
Rev:B
Nov 2008
SPX29500/01/02/03 5A Low Dropout Voltage Regulator
©
Copyright 2008
Exar
Corporation
5
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