ZHCSCB9D April 2014 – December 2019 TPS22965-Q1
A capacitor to GND on the CT pin sets the slew rate. The voltage on the CT pin can be as high as 12 V. Therefore, the minimum voltage rating for the CT cap must be 25 V for optimal performance. An approximate formula for the relationship between CT and slew rate when VBIAS is set to 5 V is shown in Equation 1. This equation accounts for 10% to 90% measurement on VOUT and does NOT apply for CT = 0 pF. Use Table 1 to determine rise times for when CT = 0 pF.
Rise time can be calculated by multiplying the input voltage by the slew rate. Table 1 contains rise time values measured on a typical device. The rise times listed in Table 1 are only valid for the power-up sequence where VIN and VBIAS are already in steady state condition before the ON pin is asserted high.
|CT (pF)||RISE TIME (µs) 10% - 90%, CL = 0.1 µF, CIN = 1 µF, RL = 10 Ω, VBIAS = 5 V (1)|
|VIN = 5 V||VIN = 3.3 V||VIN = 1.8 V||VIN = 1.5 V||VIN = 1.2 V||VIN = 1.05 V||VIN = 0.8 V|