AN4402 datasheet(29/39 Pages) STMICROELECTRONICS

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AN4402

Energy capability and load compatibility

Step 1: Calculation of tDEMAG and EDEMAG

The demagnetization energy and the demagnetization time under the conditions listed in

Table 12 are given by Equation 19 and Equation 11:

EDEMAG_LS = 83.6 mJ and tDEMAG_LS = 11.7 ms with VBAT,MAX = 24 V

EDEMAG_LS = 16.6 mJ and tDEMAG_LS = 4.2 ms with VBAT,TYP = 13.5 V

The validity condition of Equation 19 is satisfied since RP > 21 Ω (for VBAT = 24 V) and

RP > 74 Ω (for VBAT = 13.5 V).

Step 2: Maximum energy capability of the L99MC6 at the relevant tDEMAG

Considering the type of output, the relevant diagram of the datasheet is: “Configurable

switch LSD – Maximum turn-off current versus inductance” (Figure 16).

Note:

If the considered output is one of the fixed low-side switches (outputs 4, 5, 6) or one of the

outputs configured as high-side driver, the relevant diagrams are respectively “Fixed LSD

switch – Maximum turn-off current versus inductance” and “Configurable switch HSD–

Maximum turn-off current versus inductance”.

Figure 16. Datasheet L99MC6 - Inductive energy capability of configurable channels,

configured as low-side switch

VBAT,MAX (jump start)

24V

 I

L0 @VBAT,MAX = 0.522A, low probability of occurrence

VBAT,TYP

13.5V

 I

L0 @VBAT,TYP = 0.293A, nominal conditions

Table 12. Application conditions (continued)

Parameter

Value

AN4402 Datasheet(PDF) 29 Page - STMicroelectronics