SDAA267 January   2026 TCA9539-Q1 , TCA9539A-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction to TCA9539A-Q1 I2C GPIO expander
  5. 2Key Specification Comparison: TCA9539A-Q1 vs TCA9539-Q1
    1. 2.1 I²C Addressing Scheme and Compatibility
    2. 2.2 Multidevice and Zonal Architectures
  6. 3Why Use Interrupts with I²C GPIO Expanders?
  7. 4Application Examples Using TCA9539A-Q1
    1. 4.1 Zonal Controller
    2. 4.2 Infotainment and ADAS Peripheral Control
    3. 4.3 Automotive Body Control Module (BCM)
    4. 4.4 Audio and Peripheral Monitoring
  8. 5Summary
  9. 6References

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.

Table 2-2 I²C Address Scheme: TCA9539-Q1 (TCA9539QPWRQ1) vs TCA9539A-Q1 (TCA9539AQPWRQ1 and TCA9539BQPWRQ1)
Parameter TCA9539-Q1 TCA9539A-Q1
Orderable part number TCA9539QPWRQ1 Orderable part number TCA9539AQPWRQ1 Orderable part number TCA9539BQPWRQ1
I²C target addres scheme
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)
L H 117 (decimal)
75 (hex)		 L H 117 (decimal)
75 (hex)		 L H 113 (decimal)
71 (hex)
H L 118 (decimal)
76 (hex)		 H L 118 (decimal)
76 (hex)		 H L 114 (decimal)
72 (hex)
H H 119 (decimal)
77 (hex)		 H H 119 (decimal)
77 (hex)		 H H 115 (decimal)
73 (hex)
Number of I²C Addresses Four addresses Four addresses Four addresses
Eight addresses