ZHCSCK8G May 2014 – October 2017 LP8860-Q1
PRODUCTION DATA.
The boost switch FET gate driver is powered typically from VDD voltage. When the VDD voltage is not high enough to drive the boost FET gate, the charge pump can be used to increase gate-driver voltage.
The charge pump effectively doubles the VDD voltage for gate driver. Maximum DC output current is 50 mA. Boost driver voltage selection bit BOOST_GD_VOLT must be set to 1 before enabling the charge pump. If VDD voltage is 5 V, the charge pump is not typically needed. In this case, a flying capacitor is not necessary, and the charge pump output CPUMP pin must be connected to the VDD input pin.
CP_2X_CLK | FREQUENCY (kHz) |
---|---|
00 | 104 |
01 | 208 |
10 | 417 |
11 | 833 |
Square-waveform (SQW) output provides a 100-kHz square wave signal (1 mA max) with amplitude equal to the charge pump output voltage. When the charge pump is disabled, amplitude of this voltage is equal to VDD. This signal can be used to generate low-current voltage rails; for example, a gate-reference voltage for output protective FET (Figure 61) or for using nMOSFET as power-line FET (Figure 25). Figure 23 and Figure 24 show examples of possible connections.