AN4043 datasheet(25/60 Pages) STMICROELECTRONICS

номер детали	AN4043

подробное описание детали	In recent years the variable speed motor control market has required high performance

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25 / 60 page

AN4043

Electrical characteristics and functions

Doc ID 022726 Rev 2

25/60

Equation 2

●

t3: the SD signal reaches the lower threshold Vsd_L_THR and the control unit switches

off the input HIN and LIN. The smart shutdown is disabled (M1 off) and SD can rise up

with a time constant

B, given by:

Equation 3

●

t4: when the SD signal reaches the upper threshold Vsd_H_THR, the system is re-

enabled.

2.3.8

Current sensing shunt resistor selection

As previously discussed, the shunt resistors RSHUNT externally connected between the N

pin and ground (see

Figure 9) are used to realize the overcurrent detection.

When the output current exceeds the short-circuit reference level (ISC), the CIN signal

overtakes the VREF value and the short-circuit protection is active. For a reliable and stable

operation the current sensing resistor should be a high quality, low tolerance non-inductive

type. In fact, stray inductance in the circuit, which includes the layout, the RC filter, and also

the shunt resistor, must be minimized in order to avoid undesired short-circuit detection.

For these reasons, the shunt resistor and the filtering components must be placed as close

as possible to the SLLIMM-nano pins, for additional suggestions refer to

Section 5.1: Layout

suggestions.

()

⋅

Figure 15.

Timing chart of smart shutdown function

AN4043 датащи(PDF) 25 Page - STMicroelectronics