TL750M05-Q1 Datasheet, PDF (6/23 Pages) Texas Instruments – AUTOMOTIVE LOW-DROPOUT VOLTAGE REGULATORS

TL750Mxx-Q1, TL751Mxx-Q1
SGLS312J – SEPTEMBER 2005 – REVISED JUNE 2011
PARAMETER MEASUREMENT INFORMATION
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The TL750Mxx and TL751Mxx are low-dropout regulators. The output capacitor value and the parasitic
equivalent series resistance (ESR) affect the bandwidth and stability of the control loop for these devices. For
this reason, the capacitor and ESR must be carefully selected for a given operating temperature and load range.
Figure 2 and Figure 3 can be used to establish the appropriate capacitance value and ESR for the best regulator
transient response.
Figure 2 shows the recommended range of ESR for a given load with a 10-µF capacitor on the output. Figure 2
also shows a maximum ESR limit of 2 Ω and a load-dependent minimum ESR limit.
For applications with varying loads, the lightest load condition should be chosen because it is the worst case.
Figure 3 shows the relationship of the reciprocal of ESR to the square root of the capacitance, with a minimum
capacitance limit of 10 µF and a maximum ESR limit of 2 Ω. This figure establishes the amount that the minimum
ESR limit shown in Figure 2 can be adjusted for different capacitor values. For example, where the minimum
load needed is 200 mA, Figure 2 suggests an ESR range of 0.8 Ω to 2 Ω for 10 µF. Figure 3 shows that
changing the capacitor from 10 µF to 400 µF can change the ESR minimum by greater than 3/0.5 (or 6).
Therefore, the new minimum ESR value is 0.8/6 (or 0.13 Ω). This allows an ESR range of 0.13 Ω to 2 Ω,
achieving an expanded ESR range by using a larger capacitor at the output. For better stability in low-current
applications, a small resistance placed in series with the capacitor (see Table 1) is recommended, so that ESRs
better approximate those shown in Figure 2 and Figure 3.
MANUFACTURER
AVX
KEMET
Table 1. Compensation for Increased Stability at Low Currents
CAPACITANCE
15 µF
33 µF
ESR TYP
0.9 Ω
0.6 Ω
PART NUMBER
TAJB156M010S
T491D336M010AS
ADDITIONAL RESISTANCE
1Ω
0.5 Ω
Applied Load
∆I_L
Current
Load
Voltage
∆V_L
Figure 1.
∆V_L = ∆I_L × ESR
6
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