MC33993DWB View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

Manufacturer

MC33993DWB

MULTIPLE SWITCH DETECTION INTERFACE

Motorola => Freescale 

DEVICE OPERATION

Power Supply

Normal Mode

The 33993 is designed to operate from 5.5 V to 40 V on the

VPWR pin. Characteristics are provided from 8.0 V to 16 V for

the device. Switch contact currents and the internal logic supply

are generated from the VPWR pin. The VDD supply pin is used to

set the SPI communication voltage levels, current source for the

SO driver, and pull-up current on INT and CS.

VDD supply may be removed from the device to reduce

quiescent current. If VDD is removed while the device is in

Normal mode, the device will remain in Normal mode. If VDD is

removed in Sleep mode, the device will remain in Sleep mode

until wake-up input is received (WAKE high to low, switch input

or interrupt timer expires).

Removing VDD from the device disables SPI communication

and will not allow the device to wake up from INT and CS pins.

Power-ON Reset (POR)

Applying VPWR to the device will cause a Power-ON Reset

and place the device in Normal mode.

Default settings from Power-ON Reset via VPWR or Reset

Command are as follows:

• Programmable Switch – Set to Switch to Battery

• All Inputs Set as Wake-Up

• Wetting Current On (16 mA)

• Wetting Current Timer On (20 ms)

• All Inputs Tri-State

• Analog Select 00000 (No Input Channel Selected)

Modes of Operation

The 33993 has two operating modes, Normal mode and

Sleep mode. A discussion on Normal mode begins below.

A discussion on Sleep mode begins on page 18.

Normal mode may be entered by the following events:

• Application of VPWR to the IC

• Change-of-Switch State (when enabled)

• Falling Edge of WAKE

• Falling Edge of INT (with VDD = 5.0 V and WAKE at

Logic [1])

• Falling Edge of CS (with VDD = 5.0 V)

• Interrupt Timer Expires

Only in Normal mode with VDD applied can the registers of the

33993 be programmed through the SPI.

The registers that may be programmed in Normal mode are

listed below. Further explanation of each register is provided in

subsequent paragraphs.

• Programmable Switch Register (Settings Command)

• Wake-Up/Interrupt Register (Wake-Up/Interrupt

Command )

• Wetting Current Register (Metallic Command)

• Wetting Current Timer Register (Wetting Current Timer

Enable Command)

• Tri-State Register (Tri-State Command)

• Analog Select Register (Analog Command)

• Calibration of Timers (Calibration Command)

• Reset (Reset Command)

Figure 4, page 8, is a graphical description of the device

operation in Normal mode. Switch states are latched into the

input register on the falling edge of CS. The INT to the MCU is

cleared on the rising edge of CS. However, INT will not clear on

rising edge of CS if a switch has closed during SPI

communication (CS low). This prevents switch states from

being missed by the MCU.

Programmable Switch Register

Inputs SP0 to SP7 may be programmable for switch-to-

battery or switch-to-ground. These inputs types are defined

using the settings command (refer to Table 1). To set an SPn

input for switch-to-battery, a logic [1] for the appropriate bit must

be set. To set an SPn input for switch-to-ground, a logic [0] for

the appropriate bit must be set. The MCU may change or

update the Programmable Switch Register via software at any

time in Normal mode. Regardless of the setting, when the SPn

input switch is closed a logic [1] will be placed in the Serial

Output Response Register (refer to Table 12, page 17).

Table 1. Settings Command

Settings Command

Not used

Battery/Ground Select

23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

0 0 0 0 0 0 0 1 X X X X X X X X sp7 sp6 sp5 sp4 sp3 sp2 sp1 sp0

33993/D

12

MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

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