MC33972A FREESCALE [Freescale Semiconductor, Inc], MC33972A Datasheet - Page 23

• Manufacturer Part Number: MC33972A
• Description: Multiple Switch Detection Interface with Suppressed Wake-Up
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

VBAT
inputs tri-state) required to set up the device to drive a
MOSFET are as follows:
disable), the MOSFET gate will be pulled to ground. From this
point forward the MOSFET may be turned on and off by
sending the settings command :
open load detection. This is done by using an SGn input
comparator. With the SGn input in tri-state, the load will pull
up the SGn input to battery. With open load the SGn pin is
pulled down to ground through an external resistor. The open
load is indicated by a logic [1] in the SO data bit.
voltage in the MOSFET ON state. By sourcing 2.0mA of
Analog Integrated Circuit Device Data
Freescale Semiconductor
The sequence of commands (from Normal Mode with
• wetting current timer enable command – Disable SPn
• metallic command – Set SPn to 16mA or 2.0mA gate
• settings command – Set SPn as switch-to-battery (refer
• tri-state command – Disable tri-state for SPn (refer to
After the tri-state command has been sent (tri-state
• settings command – SPn as switch-to-ground
• settings command – SPn as switch-to-battery
Monitoring of the MOSFET drain in the OFF state provides
The analog command may be used to monitor the drain
wetting current timer (refer to
drive current (refer to
to
Table
(MOSFET ON).
(MOSFET OFF).
Table
Figure 15. MOSFET or LED Driver Output
10, page 16).
6, page 14).
100kΩ
1.5kΩ
SG13
SG0
SP0
Table
16
mA
16
mA
16
mA
16
mA
V
V
V
PWR
8, page 15).
PWR
PWR
4.0V Ref
4.0V Ref
Table
V
V
V
PWR
PWR
PWR
4.0V
2.0
mA
2.0mA
2.0
mA
2.0
mA
Ref
Comparator
Comparator
9, page 15).
Comparator
+
-
+
-
+
-
To SPI
To SPI
SG13
To SPI
SG0
SG0
AMUX
current to the 1.5kΩ resistor, the analog voltage on the SGn
pin will be approximately:
does the voltage on the SGn pin. With the SGn pin selected
as analog, the MCU may perform the A / D conversion.
loads is not recommended. Inductive flyback voltages greater
than V
signals from one module to another. Operation is similar to
the gate control of a MOSFET.
using the tri-state command :
commands in Normal Mode.
MULTIPLE 33972 DEVICES IN A MODULE SYSTEM
Mode operation may be done in several ways.
shows several system configurations for power between the
MCU and the 33972 and their specific requirements for
functionality.
Table 21. Sleep Mode Power Supply
SPI control may be done in parallel or serial. However when
parallel mode is used, each device is addressed
independently (refer to
Therefore when sending the sleep command, one device will
enter sleep before the other. For multiple devices in a system,
it is recommended that the devices are controlled in serial (S0
MCU
5.0V
5.0V
V
As the voltage on the drain of the MOSFET increases, so
Using this method for controlling unclamped inductive
The SP0 : SP7 pins of this device may also be used to send
• For LED applications a resistor in series with the LED is
• wetting current timer enable command – Disable SGn
• metallic command – Set SGn to 16mA.
From this point forward the LED may be turned on and off
• tri-state command – Disable tri-state for SGn (LED ON).
• tri-state command – Enable tri-state for SGn (LED
These parameters are easily programmed via SPI
Connecting power to the 33972 and the MCU for Sleep
Multiple 33972 devices may be used in a module system.
0V
0V
DD
recommended but not required. The switch-to-ground
inputs are recommended for LED application. To drive
the LED use the following commands:
wetting current timer.
OFF).
PWR
33972
5.0V
5.0V
V
may damage the IC.
0V
0V
DD
V
SGn
All wake-up conditions apply. (Refer to
Mode, page 19.)
SPI wake-up is not possible.
Sleep Mode not possible. Current from
up will flow through MCU to V
switched off. Negative edge of
33972 in Normal Mode.
SPI wake-up is not possible.
= I
MCU Interface
SGn
x 1.5kΩ + V
Comments
TYPICAL APPLICATIONS
Description, page 13).
DS
INTRODUCTION
DD
CS
Table 21
that has been
will put
CS
Sleep
33972
pull-
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