MAX20002CATPC datasheet(13/19 Pages) MAXIM

13 / 19 page

Spread-Spectrum Option

The spread spectrum can be enabled on the device

using a pin. When the SPS pin is pulled high the spread

spectrum is enabled and the operating frequency is varied

±3% centered on FOSC. The modulation signal is a trian-

gular wave with a period of 110μs at 2.2MHz. Therefore,

FOSC ramps down 3% and back to 2.2MHz in 110μs and

also ramps up 3% and back to 2.2MHz in 110μs. The

cycle repeats.

For operations at FOSC values other than 2.2MHz, the

modulation signal scales proportionally (e.g., at 400kHz,

the 110μs modulation period increases to 110μs x

2.2MHz/0.4MHz = 550μs).

The internal spread spectrum is disabled if the devices

are synchronized to an external clock. However, the

devices do not filter the input clock on the FSYNC pin and

pass any modulation (including spread spectrum) present

on the driving external clock.

Internal Oscillator (FOSC)

The switching frequency (fSW) is set by a resistor (RFOSC)

connected from FOSC to AGND. For example, a 400kHz

switching frequency is set with RFOSC = 73.2kΩ. Higher

frequencies allow designs with lower inductor values and

less output capacitance. Consequently, peak currents and

I2R losses are lower at higher switching frequencies, but

core losses, gate-charge currents, and switching losses

increase.

Overtemperature Protection

Thermal overload protection limits the total power

dissipation in the device. When the junction temperature

exceeds 175°C (typ), an internal thermal sensor shuts

down the internal bias regulator and the step-down

converter, allowing the IC to cool. The thermal sensor

turns on the IC again after the junction temperature cools

by 15°C.

Applications Information

Setting the Output Voltage

Connect FB to BIAS for a fixed +5V/3.3V output voltage.

To set the output to other voltages between 1V and 10V,

connect a resistive divider from output (OUT) to FB to

AGND (Figure 2). Select RFB2 (FB to AGND resistor) less

than or equal to 500kΩ. Calculate RFB1 (OUT to FB resis-

tor) with the following equation:

OUT

FB1

FB2

-1





















where VFB = 1V (see the Electrical Characteristics

table).

Figure 2. Adjustable Output-Voltage Setting

RFB1

RFB2

VOUT

MAX20002

MAX20003

www.maximintegrated.com

Maxim Integrated │ 13

MAX20002/MAX20003

36V, 220kHz to 2.2MHz, 2A/3A Fully

Integrated Step-Down Converters

with 15μA Operating Current

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