OUT

REF

FBT

OUT

OUT

FF

V

V

R

120

C

V

C

˜

˜

˜

2

I

I

OUT

RMS

#

20

LM60440, LM60430

SNVSBN5A – FEBRUARY 2020 – REVISED JUNE 2020

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Product Folder Links: LM60440 LM60430

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ceramic capacitor is chosen. The 220 nF must also be rated at 50 V with an X7R dielectric. The WQFN package

provides two input voltage pins and two power ground pins on opposite sides of the package. This allows the

input capacitors to be split, and placed optimally with respect to the internal power MOSFETs, thus improving the

effectiveness of the input bypassing. In this example, a single 4.7-µF and two 100-nF ceramic capacitors at each

VIN/PGND location.

Many times, it is desirable to use an electrolytic capacitor on the input in parallel with the ceramics. This is

especially true if long leads/traces are used to connect the input supply to the regulator. The moderate ESR of

this capacitor can help damp any ringing on the input supply caused by the long power leads. The use of this

additional capacitor also helps with momentary voltage dips caused by input supplies with unusually high

impedance.

Most of the input switching current passes through the ceramic input capacitor or capacitors. The approximate

worst case RMS value of this current can be calculated from Equation 7 and must be checked against the

manufacturers' maximum ratings.

(7)

The LM604x0 requires a bootstrap capacitor connected between the BOOT pin and the SW pin. This capacitor

stores energy that is used to supply the gate drivers for the power MOSFETs. A high-quality ceramic capacitor of

100 nF and at least 10 V is required.

9.2.2.8 VCC

The VCC pin is the output of the internal LDO used to supply the control circuits of the regulator. This output

requires a 1-µF, 16-V ceramic capacitor connected from VCC to GND for proper operation. In general, avoid

loading this output with any external circuitry. However, this output can be used to supply the pullup for the

power-good function (see the Power-Good Flag Output section). A value of 100 kΩ is a good choice in this case.

The nominal output voltage on VCC is 5 V; see the Electrical Characteristics for limits. Do not short this output to

ground or any other external voltage.

The value found with Equation 8 is a starting point; use lower values to determine if any advantage is gained by

with Feed-forward Capacitor Application Report is helpful when experimenting with a feedforward capacitor.

(8)

9.2.2.10 External UVLO

In some cases, an input UVLO level different than that provided internal to the device is needed. This can be

accomplished by using the circuit shown in Figure 10. The input voltage at which the device turns on is