SC1540
SC1540A
2000 SEMTECH CORP.
300mA AND 500mA LOW DROPOUT
VOLTAGE REGULATORS WITH ENABLE
PRELIMINARY - May 1, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
1
Notes:
(1) 2 inch square of 1/16" FR-4, double sided, 1 oz.
minimum copper weight.
ABSOLUTE MAXIMUM RATINGS
DESCRIPTION
The SC1540 and SC1540A are high performance low
dropout positive voltage regulators designed for use in
applications where power management is critical, such
as battery powered systems. Additionally, the
SC1540(A) provides excellent regulation over varia-
tions in line, load and temperature. Outstanding fea-
tures include low dropout performance at rated current,
fast transient response, internal current limiting and
thermal shutdown protection of the output device. A
very low quiescent current of 10A in shutdown mode
reduces power dissipation. With three voltage options
available, the SC1540(A) comes in the popular SO-8
surface mount package.
APPLICATIONS
=
Active SCSI termination
=
Low voltage microcontrollers
=
Switching power supply post-regulator
Parameter
Symbol
Maximum
Units
Maximum Input Pin
Voltage
VIN, EN
7
V
Power Dissipation
P
D
Internally
Limited
W
Thermal Resistance
Junction to Case
SO-8
JC
47
C/W
Thermal Resistance
Junction to Ambient
SO-8
(1)
JA
65
C/W
Operating Junction
Temperature Range
T
J
0 to 125
C
Storage Temperature
Range
T
STG
-65 to 150
C
Lead Temperature
(Soldering) 10 Sec
T
LEAD
260
C
ORDERING INFORMATION
Notes:
(1) Where X.X denotes voltage options. Available voltages
are: 1.8V, 2.5V and 3.3V. Contact factory for additional
voltage options.
(2) Only available in tape and reel packaging (suffix `.TR')
e.g. SC1540CS-X.X-.TR.
DEVICE
(1)(2)
OUTPUT CURRENT
PACKAGE
SC1540CS-X.X
300mA
SO-8
SC1540ACS-X.X
500mA
SO-8
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
FEATURES
=
Low dropout performance, 1.3V max
=
Full current rating over line and temperature
=
Fast transient response
=
+
2% total output regulation over line, load and
temperature
=
10A max. quiescent current in shutdown
=
Three fixed output voltages
=
Line regulation 0.2% max.
=
Load regulation 0.4% max.
=
SO-8 package
BLOCK DIAGRAM
PIN CONFIGURATIONS
SO-8
Top View
SC1540
SC1540A
2000 SEMTECH CORP.
300mA AND 500mA LOW DROPOUT
VOLTAGE REGULATORS WITH ENABLE
PRELIMINARY - May 1, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
2
NOTES:
(1) Low duty cycle pulse testing with Kelvin connections required.
(2)
V
OUT
,
V
REF
= 1%
(3) Bandwidth of 10 Hz to 10kHz.
(4) 120Hz input ripple.
ELECTRICAL CHARACTERISTICS
Unless otherwise specified: I
O
= 0mA to 300mA (500mA for SC1540A), EN = VIN
1.5V Option: VIN
= 2.9V to 7.0V
2.5 Option: VIN = 3.9V to 7.0V
3.3V Option: VIN
= 4.7V to 7.0V
Values in bold apply over full operating temperature range.
Test Conditions
Test Limits
Parameter
Symbol
Min
Typ
Max
Units
Output Voltage
(1)
VO
VIN = 5V, I
O
= 0mA
0.99|VO|
VO
1.01|VO|
V
0.98|VO|
VO
1.02|VO|
Line Regulation
(1)
REG
(LINE)
I
O
= 10mA
0.035
0.2
%
Load Regulation
(1)
REG
(LOAD)
VIN = 5V
0.2
0.4
%
Dropout Voltage
(1)(2)
SC1540
SC1540A
V
D
I
O
= 300mA
I
O
= 500mA
1.10
1.30
V
Current Limit
(1)
SC1540
SC1540A
I
CL
330
550
mA
Quiescent Current
I
Q
VIN = 5V, EN = VIN
5
7
mA
10
VIN = 5V, EN < 0.25V
6
8
A
10
Enable Pin Control Voltage
EN
Device OFF
0.25
0.45
V
Device ON
(VO+0.5) (VO+0.8)
Enable Pin Current
I
EN
EN = 0V, VIN = 5V (OFF)
0.1
1.0
A
EN = VIN = 5V (ON)
15
25
Temperature Coefficient
T
C
0.005
%/C
Temperature Stability
T
S
0.5
%
RMS Output Noise
(3)
V
N
0.003
%V
O
Ripple Rejection Ratio
(4)
R
A
VIN = 5V
60
72
dB
SC1540
SC1540A
2000 SEMTECH CORP.
300mA AND 500mA LOW DROPOUT
VOLTAGE REGULATORS WITH ENABLE
PRELIMINARY - May 1, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
3
TYPICAL APPLICATION
VOUT
VIN
ENABLE SIGNAL
U1
SC1540(A)
VIN
EN GND
VO
C2
10uF min.
C1
10uF
Tantalum
Tantalum
NOTES
(1) Input and output capacitors should be located close to the device.
(2) Connect all pins to PCB for optimal thermal characteristics.
(3) Increasing the output capacitor value will improve the overall transient response.
(4) The device is enabled when EN = VIN, and shut down when EN is pulled to ground. EN should not be taken
higher than VIN. A CMOS signal referenced to VIN would be ideal for switching the SC1540(A) on and off.
SC1540
SC1540A
2000 SEMTECH CORP.
300mA AND 500mA LOW DROPOUT
VOLTAGE REGULATORS WITH ENABLE
PRELIMINARY - May 1, 2000
652 MITCHELL ROAD NEWBURY PARK CA 91320
4
OUTLINE DRAWING - SO-8
JEDEC
REF: MS-012AA
LAND PATTERN - SO-8
(1)
Note:
(1) More copper area should be used to lower R
TH(J-A)
as needed.
ECN00-1038
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