MC33993DWB Ver la hoja de datos (PDF) - Motorola => Freescale

Número de pieza

componentes Descripción

Fabricante

MC33993DWB

MULTIPLE SWITCH DETECTION INTERFACE

Motorola => Freescale 

VBAT

1.5 kΩ

SG0

VPWR VPWR

16

2.0

mA

mA

SG0

100 kΩ

SP0

4.0 V Ref

+

-

To SPI

Comparator

VPWR VPWR

16

2.0

mA

mA

SG0

4.0 V

+

-

To SPI

16

Ref

Comparator

mA

2.0 mA

AMUX

SG13

VPWR VPWR

16

2.0

mA

mA

SG13

4.0 V Ref

+

-

To SPI

Comparator

Figure 12. MOSFET or LED Driver Output

The sequence of commands (from Normal mode with inputs

tri-state) required to set up the device to drive a MOSFET are

as follows:

• wetting current timer enable command –Disable SPn

wetting current timer (refer to Table 4, page 14).

• metallic command –Set SPn to 16 mA or 2.0 mA gate

drive current (refer to Table 3, page 13).

• settings command –Set SPn as switch-to-battery (refer to

Table 1, page 12).

• tri-state command –Disable tri-state for SPn (refer to

Table 5, page 14).

After the tri-state command has been sent (tri-state 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:

• settings command –SPn as switch-to-ground (MOSFET

ON).

• settings command –SPn as switch-to-battery (MOSFET

OFF).

Monitoring of the MOSFET drain in the OFF state provides

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.

The analog command may be used to monitor the drain

voltage in the MOSFET ON state. By sourcing 2.0 mA of current

to the 1.5 kΩ resistor, the analog voltage on the SGn pin will be

approximately:

VSGn = ISGn x 1.5 kΩ + VDS

As the voltage on the drain of the MOSFET increases, so

does the voltage on the SGn pin. With the SGn pin selected as

analog, the MCU may perform the A/D conversion.

Using this method for controlling unclamped inductive loads

is not recommended. Inductive flyback voltages greater than

VPWR may damage the IC.

The SP0–SP7 pins of this device may also be used to send

signals from one module to another. Operation is similar to the

gate control of a MOSFET.

For LED applications a resistor in series with the LED is

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 enable command –Disable SGn

wetting current timer.

• metallic command –Set SGn to 16 mA.

From this point forward the LED may be turned on and off using

the tri-state command:

• tri-state command –Disable tri-state for SGn (LED ON).

• tri-state command –Enable tri-state for SGn (LED OFF).

These parameters are easily programmed via SPI commands

in Normal mode.

Multiple 33993 Devices in a Module System

Connecting power to the 33993 and the MCU for Sleep mode

operation may be done in several ways. Table 16 shows

several system configurations for power between the MCU and

the 33993 and their specific requirements for functionality.

Table 16. Sleep Mode Power Supply

MCU

VDD

5.0 V

33993

VDD

5.0 V

Comments

All wake-up conditions apply. (Refer to Sleep

Mode, page 18.)

5.0 V

0V

0V

5.0 V

SPI wake-up is not possible.

Sleep mode not possible. Current from CS pull

up will flow through MCU to VDD that has been

switched off. Negative edge of CS will put 33993

in Normal mode.

0V

0 V SPI wake-up is not possible.

33993/D

22

MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

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