pca9548ad NXP Semiconductors, pca9548ad Datasheet - Page 7

• Manufacturer Part Number: pca9548ad
• Description: 8-channel I2c Switch With Reset
• Manufacturer: NXP Semiconductors

Philips Semiconductors
PCA9548A_2
Product data sheet
6.2.1 Control register definition
6.3 RESET input
6.4 Power-on reset
One or several SCx/SDx downstream pair, or channel, is selected by the contents of the
control register. This register is written after the PCA9548A has been addressed. The
2 LSBs of the control byte are used to determine which channel is to be selected. When a
channel is selected, the channel will become active after a STOP condition has been
placed on the I
the channel is made active, so that no false conditions are generated at the time of
connection.
Table 4.
Remark: Multiple channels can be enabled at the same time. Example: B7 = 0, B6 = 1,
B5 = 0, B4 = 0, B3 = 1, B2 = 1, B1 = 0, B0 = 0, means that channels 7, 5, 4, 1 and 0 are
disabled and channels 6, 3, and 2 are enabled. Care should be taken not to exceed the
maximum bus capacitance. Default condition is all zeroes.
The RESET input is an active LOW signal which may be used to recover from a bus fault
condition. By asserting this signal LOW for a minimum of t
its register and I
must be connected to V
When power is applied to V
a reset condition until V
and the PCA9548A register and I
states (all zeroes) causing all the channels to be deselected. Thereafter, V
lowered below 0.2 V to reset the device.
B7
X
X
X
X
X
X
X
0
1
B6
X
X
X
X
X
X
0
1
X
Control register: Write—channel selection; Read—channel status
2
C-bus. This ensures that all SCx/SDx lines will be in a HIGH state when
B5
X
X
X
X
X
0
1
X
X
2
C-bus state machine and will deselect all channels. The RESET input
Rev. 02 — 25 September 2006
B4
X
X
X
X
0
1
X
X
X
DD
DD
has reached V
through a pull-up resistor.
DD
, an internal Power-On Reset (POR) holds the PCA9548A in
B3
X
X
X
0
1
X
X
X
X
2
C-bus state machine are initialized to their default
B2
X
X
0
1
X
X
X
X
X
POR
. At this point, the reset condition is released
B1
X
0
1
X
X
X
X
X
X
8-channel I
B0
0
1
X
X
X
X
X
X
X
w(rst)L
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Command
channel 0 disabled
channel 0 enabled
channel 1 disabled
channel 1 enabled
channel 2 disabled
channel 2 enabled
channel 3 disabled
channel 3 enabled
channel 4 disabled
channel 4 enabled
channel 5 disabled
channel 5 enabled
channel 6 disabled
channel 6 enabled
channel 7 disabled
channel 7 enabled
, the PCA9548A will reset
2
C-bus switch with reset
PCA9548A
DD
must be
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