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LTC1550/LTC1551

Low Noise, Switched

Capacitor Regulated

Voltage Inverters

FEATURES

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Regulated Negative Voltage from a Single

Positive Supply

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High Charge Pump Frequency: 900kHz Typ

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Small Charge Pump Capacitors: 0.1

µF

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Requires Only Four External Capacitors

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Fixed – 4.1V or Adjustable Output

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Shutdown Mode Drops Supply Current to < 1

µA

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Output Regulation: 5%

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Available in SO-8 and 16-Lead SSOP

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GaAs FET Bias Generators

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Negative Supply Generators

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Battery-Powered Systems

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Single Supply Applications

The LTC

pump voltage inverters which include internal linear post-

regulators to minimize output ripple. Output voltages are

The LTC1550 is also available in an adjustable output

voltage version. The LTC1550/LTC1551 are ideal for use

as bias voltage generators for GaAs transmitter FETs in

portable RF and cellular telephone applications.

The LTC1550/LTC1551 operate from single 4.5V to 6.5V

supplies and draw typical quiescent currents of 4.25mA

with a 5V supply. Each device includes a TTL compatible

Shutdown pin which drops supply current to 0.2

µA typi-

cally. The LTC1550 Shutdown pin is active low (SHDN),

while the LTC1551 Shutdown pin is active high (SHDN).

Only four external components are required: an input bypass

capacitor, two 0.1

µF charge pump capacitors and a filter

capacitoratthelinearregulatoroutput.TheadjustableLTC1550

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

16-pin SSOP.

, LTC and LT are registered trademarks of Linear Technology Corporation.

10

µs/DIV

1550/51 TA02

AC COUPLED

2mV/DIV

1

2

8

7

SENSE

SHDN

LTC1551

FERRITE BEAD

GND

10

µF

1550/51 F01

0.1

µF

C1

0.1

µF

4.7

µF

3

4

6

5

0.1

µF

+