STDA017 November 2025 TPS7A33 , TPS7A4501-SP , TPS7A47 , TPS7A47-Q1 , TPS7A4701-EP , TPS7A52 , TPS7A52-Q1 , TPS7A53 , TPS7A53-Q1 , TPS7A53A-Q1 , TPS7A53B , TPS7A54 , TPS7A54-Q1 , TPS7A57 , TPS7A8300 , TPS7A83A , TPS7A84 , TPS7A84A , TPS7A85A , TPS7A90 , TPS7A91 , TPS7A92 , TPS7A94 , TPS7A96 , TPS7B7702-Q1 , TPS7H1111-SEP , TPS7H1111-SP
As described in reference [1], parallel LDOs using ballast resistors can be redrawn as shown in the schematic in Figure 2-1, and the VLOAD formula is provided in equation 1.
Figure 2-1 Equivalent Model for n Parallel LDOs Using
Ballast ResistorsAssume a parallel network in which no LDO regulates another LDO, and each feedback loop of the regulator operates independently of the others. Let ZOUTn denote the output impedance of the nth LDO in the parallel array. Since the noise analysis is performed under steady?state conditions, the load current ILOAD contains no AC component; consequently, the load current is constant (for example, the frequency content is zero). Equation 1 can therefore be simplified by applying these assumptions.
Using these assumptions, rewrite equation 1 as equations 2 and 3.
The output noise of the parallel LDOs is reduced by the square root of the number of LDOs in parallel. Fundamentally, these assumptions imply that all paralleled LDOs exhibit identical intrinsic noise (because the same LDO IC is used), operate at the same temperature, generate zero or negligible error?voltage, use the same ballast resistors with low tolerance (< 1%), and are closely matched in output impedance (ZOUT).