V
SENSE
V
OUT
V
CONTROL
V
POWER
CS5257A-1
2.5V @ 7A
300
mF
5V
Load
124
1%
124
1%
0.1
mF
5V
100
mF
5V
10
mF
10V
3.3V
5.0V
Adjust
Features
Package Options
CS5257A-1
7A LDO 5-Pin Adjustable Linear Regulator
CS5257A-1
Description
Applications Diagram
5 Lead TO-220
1
1. V
SENSE
2. Adjust
3. V
OUT
4. V
CONTROL
5. V
POWER
Tab = V
OUT
1
Rev. 4/5/99
This new very low dropout regula-
tor is designed to power the next
generation of advanced micropro-
cessors. To achieve very low
dropout, the internal pass transistor
is powered separately from the con-
trol circuitry. Furthermore, with the
control and power inputs tied
together, this device can be used in
single supply configuration and
still offer a better dropout voltage
than conventional PNP-NPN based
LDO regulators. In this mode the
dropout is determined by the mini-
mum control voltage.
It is supplied in five-terminal
TO-220 and D
2
PAK packages,
allowing for the implementation of
a remote-sense pin permitting very
accurate regulation of output volt-
age directly at the load, where it
counts, rather than at the regulator.
This remote sensing feature virtual-
ly eliminates output voltage varia-
tions due to load changes and resis-
tive voltage drops. Typical load
regulation measured at the sense
pin is 1mV for an output voltage of
2.5V with a load step of 10mA to
7A.
The very fast transient loop
response easily meets the needs of
the latest microprocessors. In addi-
tion, a small capacitor on the Adjust
pin will further improve the tran-
sient capabilities.
Internal protection circuitry pro-
vides for bust-proof operation,
similar to three-terminal regulators.
This circuitry, which includes over-
current, short circuit, supply
sequencing and overtemperature
protection will self protect the regu-
lator under all fault conditions.
The CS5257A-1 is ideal for generat-
ing a secondary 2-2.5V low voltage
supply on a motherboard where
both 5V and 3.3V are already avail-
able.
s
1.25V to 5V V
OUT
at 7A
s
V
POWER
Dropout < 0.35V @ 7A
s
V
CONTROL
Dropout < 1.10V @
7A
s
1.5% Trimmed Reference
s
Fast Transient Response
s
Remote Voltage Sensing
s
Thermal Shutdown
s
Current Limit
s
Short Circuit Protection
s
Drop-In Replacement for
LT1580
s
Backwards Compatible with
3-pin Regulators
1
5 Lead D
2
PAK
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
A Company
Electrical Characteristics:
0C T
A
70C, 0C T
J
150C, V
SENSE
= V
OUT
and V
Adj
= 0V; unless otherwise specified.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
CS5257A-1
2
Absolute Maximum Ratings
V
POWER
Input Voltage .................................................................................................................................................................6V
V
CONTROL
Input Voltage ...........................................................................................................................................................13V
Operating Junction Temperature Range...........................................................................................................0C T
J
150C
Storage Temperature Range ................................................................................................................................-65C to +150C
Lead Temperature Soldering
Wave Solder (through hole styles only) .....................................................................................10 sec. max, 260C peak
Reflow (SMD styles only) ......................................................................................60 sec. max above 183C, 230C peak
ESD Damage Threshold............................................................................................................................................................2kV
Reference Voltage
V
CONTROL
= 2.75V to 12V, V
POWER
= 2.05V to 5.5V,
1.234
1.253
1.272
V
10mA I
OUT
7A
(-1.5%)
(+1.5%)
Line Regulation
V
CONTROL
= 2.5V to 12V, V
POWER
= 1.75V to 5.5V,
.02
.20
%
I
OUT
= 10mA
Load Regulation
V
CONTROL
= 2.75V, V
POWER
= 2.05V,
.04
.20
%
(Note 3)
I
OUT
= 10mA to 7A, with remote sense
Minimum Load Current
V
CONTROL
= 5V, V
POWER
= 3.3V, V
OUT
= +1%
5
10
mA
(Note 1)
Control Pin Current
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
OUT
= 100mA
6
10
mA
(Note 2)
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
OUT
= 4A
30
60
mA
V
CONTROL
= 2.75V, V
POWER
= 1.75V, I
OUT
= 4A
33
70
mA
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
OUT
= 7A
60
180
mA
Adjust Pin Current
V
CONTROL
= 2.75V, V
POWER
= 2.05V, I
OUT
= 10mA
60
120
A
Current Limit
V
CONTROL
= 2.75V, V
POWER
= 2.05V, V
OUT
= -1.5%
7.1
10.0
A
Short Circuit Current
V
CONTROL
= 2.75V, V
POWER
= 2.05V, V
OUT
= 0V
5.0
9.0
A
Ripple Rejection
V
CONTROL
= V
POWER
= 3.25V,
60
80
dB
(Note 3)
V
RIPPLE
= 1V
P-P
@ 120Hz, I
OUT
= 4A, C
ADJ
= 0.1F
Thermal Regulation
30ms Pulse, T
A
= 25C
0.002
%/W
V
CONTROL
Dropout Voltage
V
POWER
= 2.05V, I
OUT
= 100mA
1.00
1.15
V
(Minimum V
CONTROL
-V
OUT
)
V
POWER
= 2.05V, I
OUT
= 1A
1.00
1.15
V
(Note 4)
V
POWER
= 2.05V, I
OUT
= 2.75A
1.00
1.15
V
V
POWER
= 2.05V, I
OUT
= 4A
1.00
1.15
V
V
POWER
= 2.05V, I
OUT
= 7A
1.10
1.25
V
V
POWER
Dropout Voltage
V
CONTROL
= 2.75V, I
OUT
= 100mA
.10
.15
V
(Minimum V
POWER
-V
OUT
)
V
CONTROL
= 2.75V, I
OUT
= 1A
.15
.20
V
(Note 4)
V
CONTROL
= 2.75V, I
OUT
= 2.75A
.20
.30
V
V
CONTROL
= 2.75V, I
OUT
= 4A
.26
.40
V
V
CONTROL
= 2.75V, I
OUT
= 7A
.35
.65
V
RMS Output Noise
Freq = 10Hz to 10kHz, T
A
= 25C
0.003
%V
OUT
Temperature Stability
0.5
%
Thermal Shutdown (Note 5)
150
180
210
C
Thermal Shutdown Hysteresis
25
C
V
CONTROL
Supply Only
V
CONTROL
= 13V, V
POWER
not connected,
50
mA
Output Current
V
ADJUST
= V
OUT
= V
SENSE
= 0V
CS5257A-1
Package Pin Description
PACKAGE PIN #
PIN SYMBOL
FUNCTION
3
Block Diagram
V
CONTROL
BIAS
and
TSD
V
REF
EA
IA
V
OUT
V
SENSE
Adjust
-
+
-
+
V
POWER
Electrical Characteristics:
0C T
A
70C, 0C T
J
150C, V
SENSE
= V
OUT
and V
Adj
= 0V unless otherwise specified.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
V
POWER
Supply Only
V
POWER
= 6V, V
CONTROL
not connected,
0.1
1
mA
Output Current
V
ADJUST
= V
OUT
= V
SENSE
= 0V
Note 1:
The minimum load current is the minimum current required to maintain regulation. Normally the current in the resistor divider used to set
the output voltage is selected to meet the minimum load current requirement.
Note 2:
The V
CONTROL
pin current is the drive current required for the output transistor. This current will track output current with roughly a 1:100
ratio. The minimum value is equal to the quiescent current of the device.
Note 3:
This parameter is guaranteed by design and is not 100% production tested.
Note 4:
Dropout is defined as either the minimum control voltage, (V
CONTROL)
or minimum power voltage (V
POWER
) to output voltage differential
required to maintain 1.5% regulation at a particular load current.
Note 5:
This parameter is guaranteed by design, but not parametrically tested in production. However, a 100% thermal shutdown functional test is
performed on each part.
5L TO-220
1
V
SENSE
This Kelvin sense pin allows for remote sensing of the output voltage at the
load for improved regulation. It is internally connected to the positive input
of the voltage sensing error amplifier.
2
Adjust
This pin is connected to the low side of the internally trimmed 1.5% bandgap
reference voltage and carries a bias current of about 50A. A resistor divider
from Adj to V
OUT
and from Adj to ground sets the output voltage. Also,
transient response can be improved by adding a small bypass capacitor from
this pin to ground.
3
V
OUT
This pin is connected to the emitter of the power pass transistor and pro-
vides a regulated voltage capable of sourcing 7A of current.
4
V
CONTROL
This is the supply voltage for the regulator control circuitry. For the device
to regulate, this voltage should be between 1V and 1.25V (depending on the
output current) greater than the output voltage. The control pin current will
be about 1% of the output current.
5
V
POWER
This is the power input voltage. The pin is physically connected to the collec-
tor of the power pass transistor. For the device to regulate, this voltage
should be between 0.1V and 0.65V greater than the output voltage, depend-
ing on output current. The output load current of 7A is supplied through
this pin.
CS5257A-1
4
Typical Performance Characteristics
0
10 20 30 40 50 60 70 80 90 100 110120130
-0.150
-0.125
-0.100
-0.075
-0.050
-0.025
-0.000
0.025
0.050
0.075
0.100
T
J
(
C)
Output V
oltage Deviation (%)
I
0
=10mA
V
CONTROL
=2.75V,
V
POWER
=2.05V
Reference Voltage vs Temperature
50
0
-50
-100
7
0
0
2
5
0
Time (
m
s)
Output V
oltage Deviation (mV)
Current (A)
100
1
3
4
C
OUT
=330
mF
C
POWER
=110
mF
C
CONTROL
=10
mF
C
ADJUST
=0.1
mF
V
CONTROL
=5V
V
POWER
=3.3V
V
OUT
=2.5V
Transient Response
0.0
0.5
0.0
15.0
Output Current (A)
V
POWER
-V
OUT
(V)
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
14.0
13.0
12.0
6.0
5.0
4.0
3.0
2.0
1.0
11.0
10.0
7.0
8.0
9.0
V
CONTROL
=2.75V
Short Circuit Current vs V
POWER
-V
OUT
0.0
83.0
Adjust Pin Current (
m
A)
Temperature (C)
40.0
60.0
80.0
100.0
81.0
79.0
77.0
75.0
73.0
71.0
69.0
67.0
65.0
20.0
120.0
160.0
140.0
Adjust Pin Current vs Temperature
1.0
3.0
4.0
5.0
6.0
7.0
800.000
Minimum Load Current (
m
A)
V
CONTROL
-V
OUT
(V)
9.0
10.0
11.0
2.0
8.0
850.000
900.000
950.000
1000.000
1050.000
1100.000
1150.000
1200.000
V
POWER
=3.3V
D V
OUT
=+1%
Minimum Load Current vs V
CONTROL
-V
OUT
3.00
2.00
0.00
0.000
0.060
0.070
0.080
0.090
0.100
Output Current (A)
Output V
oltage Deviation (%)
1.00
4.00
6.00
5.00
7.00
0.010
0.020
0.050
0.040
0.030
V
POWER
=2.05V
V
CONTROL
=2.75V
Load Regulation vs Output Current
CS5257A-1
5
Typical Performance Characteristics: continued
10.0
10
1
Frequency (Hz)
Ripple Rejection (dB)
20.0
30.0
40.00
60.0
70.0
80.0
90.0
10
2
10
3
10
4
10
6
10
5
50.0
V
IN
-V
OUT
=2V
I
OUT
=4A
V
RIPPLE
=1V
P-P
C
OUT
=22
mF
C
ADJ
=0.1
mF
Ripple Rejection vs Frequency
1.0
3.0
4.0
5.0
6.0
7.0
70.00
Adjust Pin Current (
m
A)
V
CONTROL
-V
OUT
(V)
9.0
71.00
72.00
73.00
74.00
75.00
10.0
11.0
2.0
8.0
V
POWER
=2.05V
IL=10mA
Adjust Pin Current vs V
CONTROL
-V
OUT
0.00
0.000
1.000
V
POWER
Dropout V
oltage (V)
Output Current
(A)
1.00
2.00
3.00
4.00
5.00
6.00
7.00
0.900
0.800
0.700
0.600
0.500
0.400
0.300
0.200
0.100
V
CONTROL
=2.75V
V
POWER
Dropout Voltage vs I
OUT
0.50
70.00
Adjust Pin Current (
m
A)
V
POWER
-V
OUT
(V)
2.50
71.00
72.00
73.00
74.00
75.00
3.50
4.50
1.50
V
CONTROL
=2.75V
IL=10mA
3.00
2.00
0.00
0.00
0.250
0.500
0.750
1.000
1.250
Output Current (A)
V
CONTROL
Drop Out V
oltage (V)
V
POWER
=2.05V
1.00
4.00
6.00
5.00
7.00
V
CONTROL
Dropout Voltage vs I
OUT
Adjust Pin Current vs V
POWER -
V
OUT
0.50
1.50
2.50
915.500
Minimum Load Current (
m
A)
V
POWER
-V
OUT
(V)
3.50
4.50
915.600
915.700
915.800
915.900
916.000
916.100
916.200
916.400
V
CONTROL
=5V
D V
OUT
=+1%
915.400
916.300
Minimum Load Current vs V
POWER
-V
OUT
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