LM2660_15 Datasheet, PDF (16/27 Pages) Texas Instruments – LM2660 Switched Capacitor Voltage Converter

LM2660
SNVS135E – SEPTEMBER 1999 – REVISED DECEMBER 2014
www.ti.com
9.2.2.2 Detailed Design Procedure
The Schottky diode D₁ is only needed for start-up. The internal oscillator circuit uses the V+ pin and the LV
pin (connected to ground in the voltage doubler circuit) as its power rails. Voltage across V+ and LV must be
larger than 1.5 V to insure the operation of the oscillator. During start-up, D₁ is used to charge up the voltage
at V+ pin to start the oscillator; also, it protects the device from turning-on its own parasitic diode and
potentially latching-up. Therefore, the Schottky diode D₁ should have enough current carrying capability to
charge the output capacitor at start-up, as well as a low forward voltage to prevent the internal parasitic
diode from turning-on. A Schottky diode like 1N5817 can be used for most applications. If the input voltage
ramp is less than 10V/ms, a smaller Schottky diode like MBR0520LT1 can be used to reduce the circuit size.
9.2.2.3 Application Curves
See Application Curves in the Voltage Inverter section.
10 Power Supply Recommendations
The LM2660 is designed to operate from as an inverter over an input voltage supply range between 1.5 V and
5.5 V when the LV pin is grounded. This input supply must be well regulated and capable to supply the required
input current. If the input supply is located far from the LM2660 additional bulk capacitance may be required in
addition to the ceramic bypass capacitors.
16
Submit Documentation Feedback
Product Folder Links: LM2660
Copyright © 1999–2014, Texas Instruments Incorporated