L99UDL01 datasheet(18/24 Pages) STMICROELECTRONICS

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Device description

L99UDL01

18/24

DB3264 Rev 3

Since this system relies on current limitation for normal running IOC can occur in one of two

ways. First, the IOC threshold can occur if the current rise time is faster than the minimum on

time (tOC_BLANKING) of the driver. This occurs when a shorted load has very little inductance.

The second method is when the integrated driver is programmed as a simple switch and

does not provide the current regulation. Then IOC is the only means of overcurrent

protection.

The external half bridges are used as a simple switch (not current regulated). However,

when both sides of the H-Bridge are set up by the use of integrated half bridges (outputs 1-

6) then one of the integrated half bridges should be programmed as a simple switch. This is

done by programming the output to be Voltage controlled (by setting the PWM_SW_x bit to

1) and setting the duty cycle to 100%.

This allows the other half bridge to provide the lock motor current regulation without

confusion.

In the case of the external half bridges Drain-Source voltage detection is implemented as an

overload protection once the driver is active. The Drain-Source threshold, VDS, and

duration, tVDS_BLANK, are both programmable with a wide range to select.

Shorted outputs may be detected in the off-state as well (see Section 2.6.3).

2.6.2

Thermal protection

There is a thermal sensor associated with each pair of drivers. There are two reported

thermal thresholds. These are thermal warning TWx and thermal shutdown TSDx.

Thermal warning only provides a SPI register indication of the condition (TWx). Thermal

shutdown either shuts down the offending half bridge or disables the entire device. This

option is programmable via SPI command. Thermal shutdown is indicated in the SPI

In the case where more than one driver is linked in parallel the hottest driver will cause a

thermal indication (TWx or TSDx). All linked drivers have their diagnostic bits linked as well.

That is, they will all demonstrate the same diagnostic state.

Drivers cannot be activated until its corresponding temperature is below thermal shutdown

threshold and corresponding fault register bit is cleared.

2.6.3

Off-state load detection

Along with the standard shorted load and thermal protections the L99UDL01 has the ability

to verify load integrity without actuating loads.

This is done by incorporating enable-able weak pull-up (ODCHx) / pull-down (ODCLx)

currents at each output. By using the weak pull-up/pull-down currents the following

conditions can be determined:



Shorted output to either ground or supply



Open load

One method would be first to bias a motor node by either a weak pull-up or weak pull-down

current then reading the Dynamic Output State (DOSx, DOS_EXTx) bits. A weak pull-up on

one output should cause all nodes associated with that output to pull high. A weak pull-down

on one output should cause all nodes associated with that output to pull low. An open circuit

or shorted output would prevent either one or the other from happening.

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