L99UDL01 datasheet(18/88 Pages) STMICROELECTRONICS

18 / 88 page

Device description

L99UDL01

18/88

DS12511 Rev 5

These outputs have over current protection, under current detection, and off-state

diagnostics. Off state diagnostics may provide for non-active detection of Lock motor status.

The output rising and falling times are controlled to provide the lowest EMI while minimizing

the switching losses. This is done by controlling the edges to smooth out the corners of the

waveform while maintaining a fast transition from one level to the other.

Active freewheeling

Active freewheeling is an automatic function. Whenever the output voltage approaches the

freewheeling rail, the freewheeling element becomes active. That is, when the High side is

driving the load and the low side MOSFET is acting as the freewheeling element the low

side MOSFET is only enabled when the voltage falls below VDS_ON_LS (50 mV typ).

Conversely, if the low side MOSFET is the driving element the high side MOSFET is not

active unless the voltage is above VDS_ON_HS (Vs-1 V typ).

This poses some limitation with respect to shorted load diagnostics. See Limitations due to

active freewheeling.

Current regulation control

All integrated outputs can work in current regulation mode. Each power MOS has a

configurable bidirectional current sense which provides an image of the load current during

on mode and recirculation phase. This current image is compared to the target value written

in the configuration register in a digital algorithm so that mean current value through the

load is equal to the chosen value.

Figure 5. Current Control Loop

10 BIT DAC

PWM

UP/DN

Counter

Setpoint

10 Bits

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