描述 Description

The TC1142 generates a regulated negative voltage from –3V to –5V at 20 mA 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 1 μA. When CCLK is pulled high, the part runs from the internal 200 KHz oscillator. The device may be run with an external clock, provided the frequency is greater than 3 KHz and less than 500 KHz. The TC1142 comes in a space-saving MSOP package.

特性 Features

Input Range 2.5V to 5.5VRegulated Output Options from –3.0 to –5.0VOutput Current 20 mA (max)200 KHz Internal Oscillator FrequencyExternal Synchronizing Clock InputLogic Level Shutdown ........ 1uA (max) Supply Current