米6体育平台手机版

SBVA100 December 2022 LP2992 , TPS786 , TPS7A30 , TPS7A3001-EP , TPS7A33 , TPS7A39 , TPS7A4501-SP , TPS7A47 , TPS7A47-Q1 , TPS7A4701-EP , TPS7A49 , TPS7A52 , TPS7A52-Q1 , TPS7A53 , TPS7A53-Q1 , TPS7A53A-Q1 , TPS7A53B , TPS7A54 , TPS7A54-Q1 , TPS7A57 , TPS7A7100 , TPS7A7200 , TPS7A7300 , TPS7A80 , TPS7A8300 , TPS7A83A , TPS7A84 , TPS7A84A , TPS7A85 , TPS7A85A , TPS7A87 , TPS7A89 , TPS7A90 , TPS7A91 , TPS7A92 , TPS7A94 , TPS7A96 , TPS7B7702-Q1 , TPS7H1111-SEP , TPS7H1111-SP , TPS7H1210-SEP

2.4 Load Current (I_LOAD) and Load Voltage (V_LOAD)

The load voltage and load current analysis for parallel LDOs using ballast resistors is discussed in detail in [see reference 4]. To recap, the number of parallel LDO's required to provide the system load current I_LOAD is a function of the parameters in Equation 5 and Equation 6, or when V_OUT and R_B are identical for each LDO, Equation 7. Additional limitations exist on the available current per LDO as described in Section 2.3.

Equation 5.

I_{O U T_n} = \frac{V_{O U T n} {- V}_{L O A D}}{R_{B n}} + \frac{V_{E n}}{R_{B n}}

Equation 6.

I_{L O A D} = \sum_{n = 1}^{n} \frac{V_{O U T n} {- V}_{L O A D} + V_{E n}}{R_{B n}}

Equation 7.

I_{O U T_n} = \frac{I_{L O A D} - (\sum_{n = 1}^{n} \frac{V_{E n}}{R_{B}})}{n} + \frac{V_{E n}}{R_{B}}

The number of parallel LDO's required to provide the system load voltage is a function of the parameters in Equation 8.

Equation 8.

V_{L O A D} = \frac{\sum_{n = 1}^{n} \frac{V_{O U T n} + V_{E n}}{R_{B n}} - I_{L O A D}}{\sum_{n = 1}^{n} \frac{1}{R_{B n}}}

Through some additional mathematics and worse case analysis we can derive the optimum ballast resistance needed to minimize the number of parallel LDO's required while simultaneously meeting the load current and load voltage requirements. The resulting formulas have been placed into an easy to use software tool available for download, see reference 5.

2.4 Load Current (ILOAD) and Load Voltage (VLOAD)

2.4 Load Current (I_LOAD) and Load Voltage (V_LOAD)