mc9s12vr48 Freescale Semiconductor, Inc, mc9s12vr48 Datasheet - Page 422

• Manufacturer Part Number: mc9s12vr48
• Description: S12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Low-Side Drivers - LSDRV (S12LSDRV1)
14.4
14.4.1
The LSDRV module provides two low-side drivers able to drive inductive loads (relays). The driver gate
can be controlled directly through register bits or alternatively by dedicated timer or PWM channels. See
PIM section for routing details.
Both drivers feature an open-load and over-current detection described in the following sub-sections. In
addition to this an active clamp (for driving relays) is protecting each driver stage. The active clamp will
turn on a low-side FET if the voltage on a pin exceeds V
14.4.2
A “High-load resistance Open Load Detection” can be enabled for each driver by setting the corresponding
LSOLEx bit (refer to
be executed when the driver is enabled and it is not being driven (LSDRx = 0). That is because the
measurement point is between the load and the driver, and the current should not go through the driver. To
detect an open-load condition the voltage will be observed at the output from the driver. Then if the driving
pin LSx stays at low voltage which is approximately LSGND, there is no load for the corresponding
low-side driver.
An open-load condition is flagged with bits LSOL0 and LSOL1 in the LSDRV Status Register (LSSR).
14.4.3
Each low-side driver has an over-current detection while enabled with a current threshold of I
If over-current is detected the related interrupt flag (LSOCIF1 or LSOCIF0) is set in the LSDRV Interrupt
Flag Register (LSIF). As long as the over-current interrupt flag remains set the related low-side driver gate
is turned off to protect the circuit.
Clearing the related over-current interrupt flag returns back the control of the gate to the selected source
in the PIM module.
14.4.4
This section describes the interrupt generated by LSDRV module. The interrupt is only available in CPU
run mode. Entering and exiting CPU stop mode has no effect on the interrupt flags.
The LSDRV interrupt vector is named in
at MCU level.
422
Functional Description
General
Open-Load Detection
Over-Current Detection
Interrupts
Although the gate is turned off by the over-current detection, the open-load
detection might not be active. Open-load detection is only active if the
selected source (e.g. PWM, Timer, LSDRx) for the low-side driver is turned
off.
Section 14.3.4, “LSDRV Configuration Register
MC9S12VR Family Reference Manual,
Preliminary - Subject to Change Without Notice
Table
14-11. Vector addresses and interrupt priorities are defined
NOTE
CLAMP
when the gate is turned off.
Rev. 2.2
(LSCR)”. This detection will only
Freescale Semiconductor
LIMLSX
.