pca9541a NXP Semiconductors, pca9541a Datasheet - Page 17

• Manufacturer Part Number: pca9541a
• Description: 2-to-1 I2c-bus Master Selector With Interrupt Logic And Reset
• Manufacturer: NXP Semiconductors

NXP Semiconductors
Table 14.
Legend: * default value
[1]
[2]
[3]
[4]
[5]
PCA9541A_3
Product data sheet
Bit
2
1
0
Default values are the same for PCA9541A/01 and PCA9541A/03.
Reading the Interrupt Status Register does not clear the MYTEST, NMYTEST or the INTIN bits. They are cleared if:
INT_IN lines goes HIGH for INTIN bit
TESTON bit is cleared for MYTEST bit
NTESTON bit is cleared for NMYTEST bit
Interrupt on a master is cleared after TESTON bit is cleared by the same master or NTESTON bit is cleared by the other master.
BUSINIT, BUSOK and BUSLOST bits in the Interrupt Status Register get cleared after a read of the same register is done. Precisely, the
register gets cleared on the second clock pulse during the read operation.
If the interrupt condition remains on INT_IN after the read sequence, another interrupt will be generated (if the interrupt has not been
masked).
Symbol
BUSOK
BUSINIT
INTIN
Register 2 - Interrupt Status (ISTAT) register bit description
[2]
[4]
[4]
8.5 Power-on reset
When power is applied to V
condition until V
internal registers are initialized to their default states, with:
Thereafter, V
Access Value
R only
R only
R only
•
•
PCA9541A/01: default Channel 0 (no STOP detect)
After power-up and/or insertion of the device in the main I
Channel 0 and the downstream slave channel are connected together.
PCA9541A/03: default ‘no channel’ (no STOP detect)
After power-up and/or insertion of the device in the main I
connected to the downstream channel. The device is ready to receive a START
condition and its address by a master.
If either register writes to its Control Register, then the connection between the
upstream and the downstream channels is determined by the values on the Control
Registers.
0*
1
0*
1
0*
1
DD
[1]
DD
must be lowered below 0.2 V to reset the device.
Description
no interrupt generated by bus sensor function
interrupt generated by bus sensor function (masked when bus
recovery/initialization requested) - Bus was not idle when the switch occurred
no interrupt generated by the bus recovery/initialization function
interrupt generated by the bus recovery/initialization function;
recovery/initialization done
no interrupt on interrupt input (INT_IN)
interrupt on interrupt input (INT_IN)
has reached V
Rev. 03 — 16 July 2009
2-to-1 I
DD
, an internal power-on reset holds the PCA9541A in a reset
2
POR
C-bus master selector with interrupt logic and reset
. At this point, the reset condition is released and the
…continued
[5]
[5]
2
2
C-bus, the upstream
C-bus, no channel will be
PCA9541A
© NXP B.V. 2009. All rights reserved.
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