ZHCSCB9E April 2014 – July 2022 TPS22965-Q1
PRODUCTION DATA
- 1 特性
- 2 應用
- 3 說明
- 4 Revision History
- 5 Device Comparison Table
- 6 Pin Configuration and Functions
- 7 Specifications
- 8 Parameter Measurement Information
- 9 Detailed Description
- 10Application and Implementation
- 11Power Supply Recommendations
- 12Layout
- 13Device and Documentation Support
- 14Mechanical, Packaging, and Orderable Information
9.3.1 Adjustable Rise Time
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. The below equations shows an approximate formula for the relationship between CT and slew rate when VBIAS is set to 5 V. This equation accounts for 10% to 90% measurement on VOUT and does not apply for CT = 0 pF. Use the below equation to determine rise times for when CT = 0 pF.
where
- SR = slew rate (in μs/V).
- CT = the capacitance value on the CT pin (in pF).
- The units for the constant 34 are μs/V. The units for the constant 0.38 are μs/(V × pF).
Rise time can be calculated by multiplying the input voltage by the slew rate. Table 9-1 contains rise time values measured on a typical device. The rise times listed in Table 9-1 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 | |
| 0 | 180 | 136 | 94 | 84 | 74 | 70 | 60 |
| 220 | 547 | 378 | 232 | 202 | 173 | 157 | 129 |
| 470 | 962 | 654 | 386 | 333 | 282 | 252 | 206 |
| 1000 | 1983 | 1330 | 765 | 647 | 533 | 476 | 382 |
| 2200 | 4013 | 2693 | 1537 | 1310 | 1077 | 959 | 766 |
| 4700 | 8207 | 5490 | 3137 | 2693 | 2200 | 1970 | 1590 |
| 10000 | 17700 | 11767 | 6697 | 5683 | 4657 | 4151 | 3350 |