a5975d STMicroelectronics, a5975d Datasheet - Page 18

• Manufacturer Part Number: a5975d
• Description: Up To 3 A Step-down Switching Regulator For Automotive Applications
• Manufacturer: STMicroelectronics

Additional features and protection
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6.1
6.2
6.3
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Additional features and protection
Feedback disconnection
If the feedback is disconnected, the duty cycle increases towards the maximum allowed
value, bringing the output voltage close to the input supply. This condition could destroy the
load.
To avoid this hazardous condition, the device is turned off if the feedback pin is left floating.
Output overvoltage protection
Overvoltage protection, or OVP, is achieved by using an internal comparator connected to
the feedback, which 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 required to adjust the output voltage
intervention is set at:
Equation 1
where R
is between the feedback pin and ground.
Zero load
Due to the fact that the internal power is a PDMOS, no bootstrap capacitor is required and
so the device works properly even with no load at the output. In this case it works in burst
mode, with a random burst repetition rate.
1
is the resistor connected between the output voltage and the feedback pin, and R
Doc ID 018760 Rev 1
V
OVP
=
1.3
⋅
R
------------------- - V
1
R
+
2
R
2
⋅
FB
(Figure
19), the OVP
A5975D
2