SDAA267 January 2026 TCA9539-Q1 , TCA9539A-Q1
2.1 I2C Addressing Scheme and Compatibility
The TCA9539AQPWRQ1 uses the same I2C addressing scheme as the TCA9539-Q1 (orderable part number TCA9539QPWRQ1), verifying full compatibility at the bus level when replacing an existing device. Both devices support programmable I2C target addresses through external address pins. The TCA9539AQPWRQ1 allows selection of up to four unique addresses on the I2C bus using A0 and A1 hardware selectable address pins similar to TCA9539QPWRQ1.
Because the address pin definition and encoding are unchanged, existing pull-up or pull-down configurations on the address pins can be reused without modification when migrating from TCA9539-Q1 to TCA9539A-Q1.
| Parameter | TCA9539-Q1 | TCA9539A-Q1 | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Orderable part number TCA9539QPWRQ1 | Orderable part number TCA9539AQPWRQ1 | Orderable part number TCA9539BQPWRQ1 | |||||||
| I2C target addres scheme |
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| I2C target addresses | A1 | A0 | ADDRESS | A1 | A0 | ADDRESS | A1 | A0 | ADDRESS |
| L | L | 116 (decimal) 74 (hex) |
L | L | 116 (decimal) 74 (hex) |
L | L | 112 (decimal) 70 (hex) |
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| L | H | 117 (decimal) 75 (hex) |
L | H | 117 (decimal) 75 (hex) |
L | H | 113 (decimal) 71 (hex) |
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| H | L | 118 (decimal) 76 (hex) |
H | L | 118 (decimal) 76 (hex) |
H | L | 114 (decimal) 72 (hex) |
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| H | H | 119 (decimal) 77 (hex) |
H | H | 119 (decimal) 77 (hex) |
H | H | 115 (decimal) 73 (hex) |
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| Number of I2C Addresses | Four addresses | Four addresses | Four addresses | ||||||
| Eight addresses | |||||||||