LTC1550/LTC1551
Low Noise, Switched
Capacitor Regulated
Voltage Inverters
FEATURES DESCRIPTION
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The LTC 1550/LTC1551 are switched capacitor charge
Regulated Negative Voltage from a Single
pump voltage inverters which include internal linear post-
Positive Supply
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regulators to minimize output ripple. Output voltages are
Low Output Ripple: Less Than 1mV Typ
P-P
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fixed at 4.1V, with ripple voltages typically below 1mV .
High Charge Pump Frequency: 900kHz Typ
P-P
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The LTC1550 is also available in an adjustable output
Small Charge Pump Capacitors: 0.1F
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voltage version. The LTC1550/LTC1551 are ideal for use
Requires Only Four External Capacitors
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as bias voltage generators for GaAs transmitter FETs in
Fixed 4.1V or Adjustable Output
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portable RF and cellular telephone applications.
Shutdown Mode Drops Supply Current to < 1A
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High Output Current: Up to 10mA, V = 5V
CC
The LTC1550/LTC1551 operate from single 4.5V to 6.5V
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Output Regulation: 5%
supplies and draw typical quiescent currents of 4.25mA
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Available in SO-8 and 16-Lead SSOP
with a 5V supply. Each device includes a TTL compatible
Shutdown pin which drops supply current to 0.2A typi-
U
cally. The LTC1550 Shutdown pin is active low (SHDN),
APPLICATIONS
while the LTC1551 Shutdown pin is active high (SHDN).
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GaAs FET Bias Generators
Only four external components are required: an input bypass
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Negative Supply Generators
capacitor, two 0.1F charge pump capacitors and a filter
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Battery-Powered Systems
capacitor at the linear regulator output. The adjustable LTC1550
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Single Supply Applications
requires two additional resistors to set the output voltage. The
LTC1550/LTC1551 will supply up to 10mA output current
with a 5V supply, while maintaining guaranteed output
regulation of 5%.
The fixed voltage LTC1550/LTC1551 are available in S0-8
plastic packages. The adjustable LTC1550 is available in a
, LTC and LT are registered trademarks of Linear Technology Corporation.
16-pin SSOP.
TYPICAL APPLICATION
4.1V Generator with 1mV Noise
V Output Noise and Ripple
P-P
OUT
1
8
V
CC
SHDN
SENSE
2 7
V CP
CC OUT
+
4.7F
C
CP
LTC1551
C
0.1F V
IN
3
6
OUT
+
C1
GND
AC COUPLED
4 5 2mV/DIV
V C1
OUT
FERRITE BEAD
V = 4.1V
OUT
I = 5mA
LOAD
C
OUT C
L
10F
0.1F
C1
1550/51 F01
0.1F
10s/DIV 1550/51 TA02
1
+
U
ULTC1550/LTC1551
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage ......................................................... 7V
Commercial Temperature Range ................. 0C to 70C
Output Voltage ................................ 0.3V to (V 14V)
Extended Commercial Operating
CC
Total Voltage, V to CP ............................................. 14V
Temperature Range (Note 3) .............. 40C to 85C
CC OUT
Input Voltage (SHDN Pin) ........... 0.3V to (V + 0.3V)
Industrial Temperature Range ................ 40C to 85C
CC
Input Voltage (REG Pin)............................ 0.3V to 12V
Storage Temperature Range ................ 65C to 150C
Output Short-Circuit Duration .............................. 30 sec
Lead Temperature (Soldering, 10 sec)................. 300C
PACKAGE/ORDER INFORMATION
TOP VIEW
ORDER ORDER
NC
1
16
V
CC
PART NUMBER PART NUMBER
TOP VIEW
+
C1
2
15
SHDN
SHDN*
1
8
SENSE
NC
3
14
REG
LTC1550CS8-4.1 LTC1550CGN
V
2
7
CP
CC OUT
V
4
13
SENSE
OUT
LTC1551CS8-4.1 LTC1550IGN
+
C1
3
6
GND
C1
5
12
ADJ
V 4 5 C1
OUT
PGND
6
11
CP
OUT
AGND
7
10
NC
S8 PACKAGE
GN PART MARKING
8-LEAD PLASTIC SO
NC 8 9 NC
*SHDN FOR LTC1550, SHDN FOR LTC1551
1550
GN PACKAGE
T = 150C, = 150C/ W
JMAX JA
16-LEAD PLASTIC SSOP
T = 150C, = 150C/ W
JMAX JA
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
V = 4.5V to 6.5V, C1 = C2 = 0.1F, C = 10F, T = 25C unless otherwise specified. (Note 3)
CC OUT A
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V Supply Voltage
CC
(LTC1550CGN/LTC1550IGN) l 2.7 6.5 V
(LTC1550CS8-4.1/LTC1551CS8-4.1) l 4.5 6.5 V
V Reference Voltage l 1.24 V
REF
I Supply Current V = 5V, V = V (LTC1550) or GND (LTC1551) l 4.25 7 mA
S CC SHDN CC
V = 5V, V = GND (LTC1550) or V (LTC1551) l 0.2 10 A
CC SHDN CC
f Internal Oscillator Frequency 900 kHz
OSC
V REG Output Low Voltage I = 1mA, V = 5V l 0.1 0.8 V
OL REG CC
I REG Sink Current V = 0.8V, V = 5V l 715 mA
REG REG CC
V SHDN Input High Voltage V = 5V l2V
IH CC
V SHDN Input Low Voltage V = 5V l 0.8 V
IL CC
I SHDN Input Current V = V l 0.1 1 A
IN SHDN CC
t Turn-On Time I = 10mA 1 ms
ON OUT
V Output Regulation 2.7V V 6.5V, 0 I 5mA l 1.575 1.5 1.425 V
OUT CC OUT
(LTC1550CGN/LTC1550IGN) 2.8V V 6.5V, 0 I 10mA l 1.575 1.5 1.425 V
CC OUT
3.5V V 6.5V, 0 I 20mA l 1.575 1.5 1.425 V
CC OUT
V Output Regulation 2.7V V 6.5V, 0 I 5mA l 2.1 2.0 1.9 V
OUT CC OUT
(LTC1550CGN/LTC1550IGN) 3.1V V 6.5V, 0 I 10mA l 2.1 2.0 1.9 V
CC OUT
3.75V V 6.5V, 0 I 20mA l 2.1 2.0 1.9 V
CC OUT
2
U W U
W
U WW