L99MD02 datasheet(8/46 Pages) STMICROELECTRONICS

8 / 46 page

Overview

L99MD02

8/46

Doc ID 16082 Rev 5

2.4

PWM mode

PWM frequency typ. 100 Hz.

Duty cycle (SPI 2bit): 15%, 30%, 45% and 60%.

Each half-bridge is independently addressable (SPI 8bit).

2.5

Current monitor

The current monitor output sources a current image at the current monitor output which has

a programmable ratio (1/250, 1/500, 1/750, 1/1000) of the instantaneous current of the

selected half bridge (high side or low side). Via SPI it can be programmed which of the

outputs will be multiplexed to the current monitor output.

The current monitor output allows a more precise analysis of the actual state of the load

rather than the detection of an open-or overload condition. For example this can be used to

detect the motor state (starting, free-running, stalled).

2.6

Inductive loads

Each half bridge is built by an internally connected high-side and a low-side power DMOS

transistor. Due to the built-in reverse diodes of the output transistors, inductive loads can be

driven at the outputs

2.7

Diagnostic functions

All diagnostic functions (over/open-load, temperature warning and thermal shutdown,

over/undervoltage) are internally filtered and the condition has to be valid for at least 32 µs

(open-load: typ. 2 ms, respectively) before the corresponding status bit in the status

registers will be set. The filters are used to improve the noise immunity of the device. Open-

load and temperature warning function are intended for information purpose and will not

change the state of the output drivers. On contrary, the overload and thermal shutdown

condition will disable the corresponding driver (overload) or all drivers (thermal shutdown),

respectively. The microcontroller has to clear the overcurrent status bit to reactivate the

corresponding driver.

2.8

Temperature warning and thermal shutdown

If the junction temperature rises above TjTW ON a temperature warning flag is set and is

detectable via the SPI. If the junction temperature increases above the second threshold

TjSD ON, the thermal shutdown bit will be set and power DMOS transistors of all output

stages are switched off to protect the device. Temperature warning flag and thermal

shutdown bits are latched. In order to reactivate the output stages, the junction temperature

must decrease below TjSD ON -TjSDHYS and the thermal shutdown bit has to be cleared by

the microcontroller.

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