MAX20004E datasheet(13/21 Pages) MAXIM

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Applications Information

Maximum Output Current

While there are device versions that supply up to 8A, there are many factors that may limit the average output current

to less than the maximum. The devices can be thermally limited based on the selected fSW, number of PCB layers,

PCB size, and the maximum ambient temperature. See the Typical Operating Characteristics section for guidance on the

maximum average current. For a more precise value, the θJA needs to be measured in the application environment.

Setting the Output Voltage

Connect FB to BIAS for a fixed 5V, 3.3V, or 3.9V output voltage. To set the output to other voltages between 1V and 5V,

connect a resistor-divider from the FB output (OUT) to GND (see Figure 1). Select RFB2 (FB to GND resistor) less than

or equal to 100kΩ. Calculate RFB1 (OUT to FB resistor) with the following equation:

Equation 1:

RFB1 = RFB2

[[VOUT

VFB

]−1

]

where VFB is the feedback regulation voltage. See the Electrical Characteristics table.

Add a capacitor, CFB1, as shown to compensate the pole formed by the divider resistance and FB pin capacitance as

follows:

Equation 2:

CFB1 = 10pF ×

[RFB2

RFB1

]

Note: Applications that use a resistor-divider to set output voltages below 4.5V should use IC versions that are

factory-trimmed for 3.3V/3.9V fixed output voltage to ensure full output current capability.

MAX20004E/

MAX20006E/

MAX20008E

RFB1

RFB2

VOUT

CFB1

Figure 1. Adjustable Output Voltage Setting

MAX20004E/MAX20006E/

MAX20008E

Automotive, 36V, 4A/6A/8A Integrated Step-Down

Converters with Integrated Compensation

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MAX20004E Datasheet(PDF) 13 Page - Maxim Integrated Products