MAX14571_13 Datasheet, PDF(12/14 Page) Maxim Integrated Products – Adjustable Overvoltage and Overcurrent Protectors with High Accuracy

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MAX14571_13 Datasheet, PDF (12/14 Pages) Maxim Integrated Products – Adjustable Overvoltage and Overcurrent Protectors with High Accuracy

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MAX14571/MAX14572/MAX14573

Adjustable Overvoltage and Overcurrent

Protectors with High Accuracy

OUT Bypass Capacitor

For stable operation over the full temperature range

and over the entire programmable current-limit range,

connect a 1FF ceramic capacitor from OUT to ground.

Excessive output capacitance can cause a false over-

current condition due to decreased dV/dt across the

capacitor. Calculate the maximum capacitive load

(CMAX) value that can be connected to OUT by using

the following formula:

CMAX (ÂµF)

ILIM(mA)

t BLANK(MIN)

VIN(V)

(ms)

For example, for VIN = 24V, tBLANK = 15ms, and ILIM =

4.2A, CMAX equals 2625FF.

Output Freewheeling Diode for

Inductive Hard Short to Ground

In applications that require protection form a sudden

short to ground with an inductive load or long cable, a

Schottky diode between the OUT terminal and ground

is recommended. This is to prevent a negative spike on

OUT due to the inductive kickback during a short-circuit

event.

Layout and Thermal Dissipation

To optimize the switch response time to output short-

circuit conditions, it is very important to keep all traces

as short as possible to reduce the effect of undesirable

parasitic inductance. Place input and output capaci-

tors as close as possible to the device (no more than

5mm). IN and OUT must be connected with wide short

traces to the power bus. During normal operation, the

power dissipation is small and the package temperature

change is minimal. If the output is continuously shorted

to ground at the maximum supply voltage, the switches

with the autoretry option do not cause thermal-shutdown

detection to trip:

P(MAX)

VIN(MAX) Ã IOUT(MAX) Ã

tRETRY + tBLANK

t BLANK

Attention must be given to the MAX14573 continuous

current-limit version when the power dissipation dur-

ing a fault condition can cause the device to reach

the thermal-shutdown threshold. Thermal vias from the

exposed pad to ground plane are highly recommended

to increase the system thermal capacitance while reduc-

ing the thermal resistance to the ambient.

ESD Test Conditions

The devices are specified for Q15kV (HBM) typical ESD

resistance on IN when IN is bypassed to ground with a

1FF low-ESR ceramic capacitor. No capacitor is required

for Q2kV (HBM) typical ESD on IN. All the pins have a

Q2kV (HBM) typical ESD protection.

HBM ESD Protection

Figure 5a shows the Human Body Model, and Figure

5b shows the current waveform it generates when dis-

charged into a low impedance. This model consists of a

100pF capacitor charged to the ESD voltage of interest,

which is then discharged into the device through a 1.5kI

resistor.

1MI

CHARGE-CURRENT-

LIMIT RESISTOR

1.5kI

DISCHARGE

RESISTANCE

HIGH-

VOLTAGE

SOURCE

100pF

STORAGE

CAPACITOR

Figure 5a. Human Body ESD Test Model

DEVICE

UNDER

TEST

IP 100%

90%

AMPERES

36.8%

10%

0 tRL

PEAK-TO-PEAK RINGING

(NOT DRAWN TO SCALE)

TIME

tDL

CURRENT WAVEFORM

Figure 5b. Human Body Current Waveform

12ââ

Maxim Integrated

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