L5970AD データシートの表示（PDF） - STMicroelectronics

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L5970AD

1.5A SWITCH STEP DOWN SWITCHING REGULATOR

STMicroelectronics 

L5970AD

3.8 THERMAL SHUTDOWN

The shutdown block generates a signal that turns off the power stage if the temperature of the chip goes higher

than a fixed internal threshold (150°C). The sensing element of the chip is very close to the PDMOS area, so

ensuring an accurate and fast temperature detection. An hysteresis of approximately 20°C avoids that the de-

vices turns on and off continuously

4 Additional Features and Protections

4.1 FEEDBACK DISCONNECTION

In case of feedback disconnection, the duty cycle increases versus the maximum allowed value, bringing the

output voltage close to the input supply. This condition could destroy the load.

To avoid this dangerous condition, the device is turned off if the feedback pin remains floating.

4.2 OUTPUT OVERVOLTAGE PROTECTION

The overvoltage protection, OVP, is realized by using an internal comparator, which input is connected to the

feedback, that turns off the power stage when the OVP threshold is reached. This threshold is typically 30%

higher than the feedback voltage.

When a voltage divider is requested for adjusting the output voltage (see test application circuit), the OVP inter-

vention will be set at:

VOVP

=

1.3

⋅

R-----1----+-----R-----2-

R2

⋅

VFB

Where R1 is the resistor connected between the output voltage and the feedback pin, while R2 is between the

feedback pin and ground.

4.3 ZERO LOAD

Due to the fact that the internal power is a PDMOS, no boostrap capacitor is required and so, the device works prop-

erly also with no load at the output. In this condition it works in burst mode, with random repetition rate of the burst.

5 Application Ideas

L5970AD belongs to L597x family.

Related part numbers are:

● L5970D: 1.5A (Isw), 250KHz Step Down DC-DC Converter in SO8

● L5972D: 2A (Isw), 250KHz Step Down DC-DC Converter in SO8

● L5973AD: 2A (Isw), 500KHz Step Down DC-DC Converter in HSOP8

● L5973D: 2.5A (Isw), 250KHz Step Down DC-DC Converter in HSOP8

In case higher current is needed, the nearest DC-DC Converter family is L497x.

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