TC1142

M Features TC1142 Package Type 8-Pin MSOP VOUT 1 C2– 2 C2+ 3 8 CCLK VIN C1+ GND Inductorless -2x Boost/Buck Regulator Input Range 2.5V to 5.5V Regulated Output Options from -3.0 to -5.0V Output Current 20mA (max) 200kHz Internal Oscillator Frequency External Synchronizing Clock Input Logic Level Shutdown - 1µA (max) Supply Current Available in 8-Pin MSOP Package TC1142 7 6 5 C1– 4 Applications Cellular Phones Battery Powered/Portable Equipment General Description The TC1142 generates a regulated negative voltage from -3V to -5V at 20mA from an input of 2.5V to 5.5V, using only three external capacitors. Other boost/buck switching regulators must use an inductor, which is larger and radiates EMI. An internal voltage comparator inhibits the charge pump when VOUT is more negative than the regulated value (per the ordering option). The values of flying capacitors C1 and C2 are chosen to be less than COUT in order to reduce the ripple generated from regulating VOUT in this manner. The TC1142 also can be used as a -1x buck regulator by omitting C2, and connecting the C2 pin to VOUT. The part goes into shutdown when the CCLK input is driven low. When in shutdown mode, the part draws a maximum of 1µA. When CCLK is pulled high, the part runs from the internal 200kHz oscillator. The device may be run with an external clock, provided the frequency is greater than 3kHz and less than 500kHz. The TC1142 comes in a space-saving MSOP package. Device Selection Table...