米6体育平台手机版

ZHCSSA9 june 2023 TPS62901-Q1

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机械数据 (封装 | 引脚)

RYT|9
- MPSS145A

散热焊盘机械数据 (封装 | 引脚)

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zhcssa9_oa

9.2.2.3.1 Output Filter and Loop Stability

The TPS62901-Q1 is designed to be stable with a range of L-C filter combinations. The LC output filters inductance and capacitance have to be considered together, creating a double pole responsible for the corner frequency of the converter using Equation 12.

Equation 12.

f_{L C} = \frac{1}{2 π \sqrt{L \times C}}

Proven nominal values for inductance and ceramic capacitance are given in Table 9-3 and are recommended for use with the effective capacitance considered to vary by +20% and –50%. Different values can work, but care has to be taken on the loop stability, which is affected. More information including a detailed LC stability matrix can be found in the Optimizing the TPS62130/40/50/60 Output Filter application report.

Table 9-3 Recommended LC Output Filter Combinations

	4.7 µF	10 µF	22 µF	47 µF	100 µF	200 µF
1 µH		√	√⁽¹⁾	√	√	√⁽³⁾
1.5 µH		√	√	√	√⁽³⁾
2.2 µH		√	√⁽²⁾	√	√⁽³⁾
3.3 µH	√	√	√	√

(1) This LC combination is the standard value and recommended for most applications with 2.5-MHz switching frequency.

(2) This LC combination is the standard value and recommended for most applications with 1-MHz switching frequency.

(3) Output capacitance must have a ESR of ≥ 10 mΩ for stable operation, see Section 9.4.2.

The TPS62901-Q1 includes an internal 3-pF feedforward capacitor, connected between the VOS and FB pins. This capacitor impacts the frequency behavior and sets a pole and zero in the control loop with the resistors of the feedback divider, per Equation 13 and Equation 14:

Equation 13.

f_{z e r o} = \frac{1}{2 π \times R_{1} \times 3 p F}

Equation 14.

f_{p o l e} = \frac{1}{2 π \times 3 p F} \times (\frac{1}{R_{1}} \times \frac{1}{R_{2}})

Although the TPS62901-Q1 devices are stable without the pole and zero being in a particular location, an external feedforward capacitor can be added to adjust their locations to the specific needs of the application can provide better performance in power save mode, improved transient response, or both. A more detailed discussion on the optimization for stability versus transient response can be found in the Optimizing Transient Response of Internally Compensated DC-DC Converters and Feedforward Capacitor to Improve Stability and Bandwidth of TPS621/821-Family application reports.