SLVAFX0 October 2024 TLV702 , TLV703 , TLV755P , TPS74401 , TPS7A13 , TPS7A14 , TPS7A20 , TPS7A21 , TPS7A49 , TPS7A52 , TPS7A53 , TPS7A53B , TPS7A54 , TPS7A57 , TPS7A74 , TPS7A83A , TPS7A84A , TPS7A85A , TPS7A91 , TPS7A92 , TPS7A94 , TPS7A96 , TPS7H1111-SP
We can use the previous equations to quickly calculate the inrush current through the LDO regulator if we know the output capacitance and load during the turn-on period. Figure 3-3 provides an example using the TPS7A20 (recall that this device includes an NR filter that also controls the turn-on time). Two 1µF capacitors are installed on the output which provide an effective capacitance of 1.4µF.
Figure 3-3 provides an example using the TPS7A84A. Recall that the TPS7A84A uses a fast-charge current source (without an NR resistor in parallel) and switches in the NR filter for steady state operation. The analysis used COUT = 67µF and the peak current (IPEAK) is well within the tolerance of the capacitors.
TPS7A20 | COUT = 1µF || 1µF |
TPS7A84A | COUT = 47µF || 10µF || 10µF |
(A.) VCM induced current spike |