JAJSUN1 データシート

JAJSUN1A May 2024 – September 2024 TPS7H1121-SP

PRODMIX

パッケージ・オプション

デバイスごとのパッケージ図は、PDF版データシートをご参照ください。

メカニカル・データ（パッケージ｜ピン）

HFT|22

サーマルパッド・メカニカル・データ

発注情報

9.2.2.3 Enable Threshold

The desired turn-on threshold is 1.35V. This means that as the V_IN rail is turned-on and begins rising, the TPS7H1121 commences turning-on as soon as V_IN reaches 1.35V. While this is not enough headroom from V_IN to V_OUT for final regulation, the regulator initiates start-up and V_IN progresses to the final voltage of 5V. If desired, a higher voltage turn-on threshold can be selected (for example, 3.5V), provided the desired voltage is below 7V.

Using Equation 1 and selecting an R_EN(TOP) value of 49.9kΩ, the R_EN(BOT) can be calculated as shown in Equation 11.

Equation 11.

R_{E N (B O T)} = \frac{V_{E N (r i s i n g)} \times R_{E N (T O P)}}{V_{I N (r i s i n g)} - V_{E N (r i s i n g)}} = \frac{0.605 V \times 49.9 k Ω}{1.35 V - 0.605 V} = 40.2 k Ω

Using E192 resistor values, R_EN(BOT) is chosen to be 40.2kΩ.

To comply with the maximum pin voltage for Enable use Equation 4. As shown in Equation 12, V_EN(final) = 2.24V which is less than the recommended maximum of 7V and above the recommended minimum final value of 0.8V.

Equation 12.

V_{E N (f i n a l)} = V_{I N (f i n a l)} \times (\frac{R_{E N (B O T)}}{R_{E N (B O T)} + R_{E N (T O P)}}) = \frac{5 V \times 40.2 k Ω}{40.2 k Ω + 49.9 k Ω} = 2.24 V