The LTC1550/LTC1551 are switched capacitor charge pump voltage inverters which include internal linear post-regulators to minimize output ripple. Output voltages are fixed at –4.1V, with ripple voltages typically below 1mVP-P. The LTC1550LCMS8 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 0.2µA typically. The LTC1550LCMS8 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 0.1µF charge pump capacitors and a filter capacitor at the linear regulator output. The adjustable LTC1550LCMS8 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 LTC1550LCMS8 is available in a 16-pin SSOP.
Feature
- Regulated Negative Voltage from a Single Positive Supply
- Low Output Ripple: Less Than 1mVP-P Typ
- High Charge Pump Frequency: 900kHz Typ
- Small Charge Pump Capacitors: 0.1µF
- Requires Only Four External Capacitors
- Fixed −4.1V or Adjustable Output
- Shutdown Mode Drops Supply Current to < 1µA
- High Output Current: Up to 10mA, VCC = 5V
- Output Regulation: 5%
- Available in SO-8 and 16-Lead SSOP
Applications
- GaAs FET Bias Generators
- Negative Supply Generators
- Battery-Powered Systems
- Single Supply Applications
