LTC1504A
500mA Low Voltage
Step-Down Synchronous
Switching Regulator
DESCRIPTION
FEATURES
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500mA Output Current at 3.3V Output The LTC 1504A is a self-contained, high efficiency syn-
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Up to 92% Peak Efficiency chronous buck switching regulator. It includes a pair of
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100% Maximum Duty Cycle on-chip 1.3W power switches, enabling it to supply up to
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Internal Reference Trimmed to 1% 500mA of load current. Efficiency peaks at 92%, minimiz-
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Output Can Source or Sink Current ing heat and wasted power. The synchronous buck archi-
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Requires as Few as Four External Components tecture allows the output to source or sink current as
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Input Voltage Range: 4V to 10V required to keep the output voltage in regulation. 100%
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Adjustable Current Limit duty cycle operation minimizes dropout voltage.
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Small SO-8 Package
The LTC1504A is available in adjustable and fixed 3.3V
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200kHz Switching Frequency Can Typically be
output versions. An adjustable current limit circuit pro-
Synchronized Up to 500kHz
vides protection from overloads. The internal 1% refer-
ence combined with a sophisticated voltage feedback loop
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provides optimum output voltage accuracy and fast load
APPLICATIONS
Daisy-Chained Control Outputs
transient response. The LTC1504A is specified to operate
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Small Portable Digital Systems
with input voltages between 4V and 10V. Contact the LTC
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Active Termination
factory for guaranteed specifications at 2.7V supply.
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Auxiliary Output Voltage Supplies
The LTC1504A is a pin-compatible, functional upgrade to
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Minimum Part Count/Size Switchers
the LTC1504.
The LTC1504A is available in a plastic SO-8 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
Minimum Part Count 5V to 3.3V Regulator 5V to 3.3V Efficiency
100
NC SHUTDOWN
90
L
EXT
I SHDN
MAX 80
50H
3.3V AT 500mA
5V V SW
CC
70
+
C
IN
LTC1504A-3.3
60
22F
GND SENSE
50
+
C
OUT
SS COMP
40
47F
30
NC 1000pF
C : AVX TPSC226M016R0375
IN
C : AVX TAJC476M010 20
OUT
L : COILTRONICS CTX50-1P 1504A TA01
EXT
10
0
10 100 500
LOAD CURRENT (mA)
1504 TA02
1
EFFICIENCY (%)
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ULTC1504A
ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER I FOR ATIO
(Note 1)
ORDER PART
TOP VIEW
Supply Voltage (V to GND)................................... 10V
CC
NUMBER
I 1 8 COMP
MAX
Peak Output Current (SW) ....................................... 1A
V 2 7 SS LTC1504ACS8
CC
Input Voltage (All Other Pins) ...... 0.3V to (V + 0.3V)
CC
LTC1504ACS8-3.3
SW 3 6 SHDN
Operating Temperature Range
LTC1504AIS8
GND 4 5 FB/SENSE*
LTC1504AC ............................................. 0 C to 70 C
LTC1504AIS8-3.3
S8 PACKAGE
LTC1504AI ......................................... 40 C to 85 C
8-LEAD PLASTIC SO
Storage Temperature Range ................. 65 C to 150 C
S8 PART MARKING
*FB FOR LTC1504A, SENSE FOR LTC1504A-3.3
Lead Temperature (Soldering, 10 sec).................. 300 C
T = 125 C, q = 90 C/W
JMAX JA
1504A 1504AI
1504A33 04AI33
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS V = 5V, T = 25 C unless otherwise specified. (Note 2)
CC A
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V Minimum Supply Voltage (Note 7) l4V
CC
V Feedback Voltage LTC1504ACS8 l 1.25 1.265 1.28 V
FB
LTC1504AIS8 l 1.23 1.265 1.29 V
D V Feedback Voltage PSRR Figure 1, 4V V 10V, LTC1504ACS8 l 1.1 1.6 %
FB CC
Figure 1, 4V V 10V, LTC1504AIS8 l 1.1 1.8 %
CC
V Sense Pin Voltage LTC1504ACS8-3.3 l 3.20 3.30 3.40 V
SENSE
D V Sense Voltage PSRR Figure 1, 4V V 10V, LTC1504ACS8-3.3 l 1.2 1.8 %
SENSE CC
Figure 1, 4V V 10V, LTC1504AIS8-3.3 l 1.2 2.0 %
CC
I Supply Current Figure 1, V = V , I = 0 (Note 4) 3 mA
CC SHDN CC OUT
Figure 1, V = V , I = 0, V /V = V (Note 4) l 0.3 0.6 mA
SHDN CC OUT FB SENSE CC
V = 0V l 1.0 20 m A
SHDN
f Internal Oscillator Frequency Commercial l 150 200 250 kHz
OSC
Industrial l 130 200 300 kHz
R Internal Switch Resistance Commercial l 1.3 2.0 W
SW
Industrial l 1.3 2.2 W
V SHDN Input High Voltage l 2.4 V
IH
V SHDN Input Low Voltage l 0.8 V
IL
I SHDN Input Current l 0.1 1 m A
IN
V Error Amplifier Positive Swing Figure 2 l 4.5 4.95 V
OH
V Error Amplifier Negative Swing Figure 2 l 0.05 0.5 V
OL
I , I Error Amplifier Output Current Figure 2 l 50 100 200 m A
OH OL
g Error Amplifier Transconductance Commercial (Note 5) l 350 600 1100 m mho
mV
Industrial (Note 5) l 300 600 1200 m mho
A Error Amplifier DC Gain (Note 5) l 40 48 dB
V
g I Amplifier Transconductance (Note 6) 2000 m mho
mI LIM
I I Sink Current V = V , Commercial l 812 16 m A
MAX MAX IMAX CC
V = V , Industrial l 812 17 m A
IMAX CC
2
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