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參數(shù)資料
| 型號(hào)： | PC33975A |
| 廠商： | 飛思卡爾半導(dǎo)體(中國(guó))有限公司 |
| 英文描述： | Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| 中文描述： | 多交換檢測(cè)接口，具有抑制喚醒和32毫安濕電流 |
| 文件頁數(shù)： | 25/32頁 |
| 文件大?。?/td> | 641K |
| 代理商： | PC33975A |
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Analog Integrated Circuit Device Data
Freescale Semiconductor
25
33975
TYPICAL APPLICATIONS
OPERATIONAL MODES
Multiple 33975 devices may be used in a module system.
SPI control may be done in parallel or serial. However when
parallel mode is used, each device is addressed
independently (refer to
MCU Interface Description
, page
13
).
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
from first device is connected to SI of second device). With
two devices, 48 clock pulses are required to shift data in.
When the
WAKE
feature is used to enable the power supply,
both
WAKE
terminals should be connected to the enable
terminal on the power supply. The
INT
terminals may be
connected to one interrupt terminal on the MCU or may have
their own dedicated interrupt to the MCU.
The transition from Normal to Sleep mode is done by
sending the
sleep command
. With the devices connected in
serial and the
sleep command
sent, both will enter Sleep
mode on the rising edge of
CS
. When Sleep mode is entered,
the
WAKE
terminal will be logic [1]. If either device wakes up,
the
WAKE
terminal will transition low, waking the other
device.
A condition exists where the MCU is sending the
sleep
command
(
CS
logic [0]) and a switch input changes state.
With this event the device that detects this input will not
transition to Sleep mode, while the second device will enter
Sleep mode. In this case two
switch status commands
must
be sent to receive accurate switch status data. The first
switch status command
will wake the device in Sleep mode.
Switch status data may not be valid from the first
switch
status command
because of the time required for the input
voltage to rise above the 4.0 V input comparator threshold.
This time is dependant on the impedance of SGn or SPn
node. The second
switch status command
will provide
accurate switch status information. It is recommended that
software wait 10 ms to 20 ms between the two
switch status
commands,
allowing time for switch input voltages to
stabilize. With all switch states acknowledged by the MCU,
the sleep sequence may be initiated. All parameters for Sleep
mode should be updated prior to sending the
sleep
command
.
The 33975 IC has an internal 5.0 V supply from the VPWR
terminal. A POR circuit monitors the internal 5.0 V supply. In
the event of transients on the VPWR terminal, an internal
reset may occur. Upon reset the 33975 will enter Normal
mode with the internal registers as defined in
Table 15
,
page
18
. Therefore it is recommended that the MCU
periodically update all registers internal to the IC.
USING THE
WAKE
FEATURE
The 33975 provides a
WAKE
output and wake-up input
designed to control an enable terminal on system power
supply. While in the Normal mode, the
WAKE
output is low,
enabling the power supply. In the Sleep mode, the
WAKE
terminal is high, disabling the power supply. The
WAKE
terminal has a passive pull-up to the internal 5.0 V supply but
may be pulled up through a resistor to V
PWR
supply (see
Figure 16
, page
26
).
When the WAKE output is not used the terminal should be
pulled up to the VDD supply through a resistor as shown in
Figure 15
, page
26
).
During the Sleep mode, a switch closure will set the
WAKE
terminal low, causing the 33975 to enter the Normal mode.
The power supply will then be activated, supplying power to
the VDD terminal and the microprocessor and the 33975. The
microprocessor can determine the source of the wake-up by
reading the interrupt flag.
COST AND FLEXIBILITY
Systems requiring a significant number of switch
interfaces have many discrete components. Discrete
components on standard PWB consume board space and
must be checked for solder joint integrity. An integrated
approach reduces solder joints, consumes less board space,
and offers wider operating voltage, analog interface
capability, and greater interfacing flexibility.
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| PC33975AEK | Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| PC33975AR2 | Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PC33975AEK | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| PC33975AR2 | 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Multiple Switch Detection Interface with Suppressed Wake-Up and 32mA Wetting Current |
| PC33981PNA/R2 | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:High-Frequency, High-Current, Self-Protected High-Side Switch (4.0 mз up to 60 kHz) |
| PC33984CHFKR2 | 制造商:Freescale Semiconductor 功能描述: |
| PC33989DW | 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:System Basis Chip with High Speed CAN Transceiver |
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