A5974D datasheet(25/46 Pages) STMICROELECTRONICS

Part #	A5974D

Description	Zero load current operation

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

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DocID018774 Rev 2

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A5974D

Application information



Switching losses due to turning ON and OFF. These are derived using the following

equation:

Equation 24

Where TRISE and TFALL represent the switching times of the power element that cause the

switching losses when driving an inductive load (see Figure 14). TSW is the equivalent

switching time.

Figure 14. Switching losses



Quiescent current losses

Equation 25

Where IQ is the quiescent current.

Example 2



VIN = 12 V



VOUT = 3.3 V



IOUT = 2.5 A

RDS(on) has a typical value of 0.25 at 25 °C and increases up to a maximum value of 0.5. at

150 °C. We can consider a value of 0.4

.

TSW is approximately 70 ns.

IQ has a typical value of 2.5 mA at VIN = 12 V.

PSW

VIN IOUT

TON TOFF



------------------------------------



FSW VIN



IOUT TSW



FSW



VIN IQ



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