L9959 datasheet(27/49 Pages) STMICROELECTRONICS

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L9959

Application information

4.2.2

Current limitation

The H-Bridge output current can be limited to three different values (see Table 15: Current

limiting). If the current reaches the current limiting threshold ICL, the output driver is

switched off after the blanking time tb, and switched on again after the current dropped

below the lower current limit hysteresis threshold (ICL – IHYS). The current limiting

thresholds can be adjusted using the resistor at pin CF. The values in Table 15 refer to a

5.1k Ohm external resistor. The current limiting threshold can be calculated by (4.5V/RCF -

IOFFSET) * (ICLx*5.1k/4.45V) from Table 15 and IOFFSET =10μA (typical). RCF is the resistor

used at pin CF.

The overcurrent threshold is not changed by RCF (see Table 16). The current limitation is

active as long as the output driver is switched on. The information that the device is in

current limitation is stored in the diagnosis register 2 (DIA_REG2).

Figure 16. Current limitation

4.2.3

Temperature dependent current reduction

If the device reaches the temperature TILR, the current will be reduced (see Figure 17:

Temperature dependent current reduction). If the temperature reaches the temperature

shutdown threshold TSD, the outputs are switched off. The current limitation information is

written into the diagnosis register 2 (DIA_REG2).

Figure 17. Temperature dependent current reduction

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