A6986H datasheet(52/71 Pages) STMICROELECTRONICS

Part #	A6986H

Description	Automotive 38 V, 2 A synchronous step-down switching regulator with 30 μA

PDF	71 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

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For example with VOUT = 3.3 V, VIN = 12 V, fSW = 500 kHz, ΔIL = 0.6 A, (resulting by the inductor value) and COUT

= 20 µF MLCC :

ΔVOUTVOUT≅ 1VOUT⋅ ΔILMAX

COUT⋅fSW=(13.3⋅ 0.6

8⋅20μF⋅500kHz)=7.5mV3.3=0.23%

(53)

The output capacitor value has a key role to sustain the output voltage during a steep load transient. When the

load transient slew rate exceeds the system bandwidth, the output capacitor provides the current to the load. In

case the final application specifies high slew rate load transient, the system bandwidth must be maximized and

the output capacitor has to sustain the output voltage for time response shorter than the loop response time.

In Table 17. Output capacitors some capacitor series are listed.

Table 17. Output capacitors

Manufacturer

Series

Cap value (μF)

Rated voltage (V)

ESR (mΩ)

MURATA

GRM32

22 to 100

6.3 to 25

GRM31

10 to 47

6.3 to 25

PANASONIC

ECJ

10 to 22

6.3

EEFCD

10 to 68

6.3

15 to 55

SANYO

TPA/B/C

100 to 470

4 to 16

40 to 80

TDK

C3225

22 to 100

6.3

A6986H

Design of the power components

DS12861 - Rev 3

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