[FAQ] TPS929120-Q1: What's the difference between TPS929120, TPS929120A, TPS929121 and TPS929121A?

Part Number: TPS929120-Q1
Other Parts Discussed in Thread: TPS929121-Q1,

For the 12-channel automotive high-side LED drivers used in automotive lighting, there are a couple of parts available, including TPS929120QPWPRQ1, TPS929120AQPWPRQ1, TPS929121QPWPRQ1 and TPS929121AQPWPRQ1. What's the difference between them?

  • Hi,

    The TPS929120-Q1 device has two orderable part numbers, TPS929120QPWPRQ1 and TPS929120AQPWPRQ1. The TPS929121-Q1 device also has two orderable part numbers, TPS929121QPWPRQ1 and TPS929121AQPWPRQ1. Here is the overall comparison table of the four parts.

    1. The difference between TPS929120-Q1 and TPS929121-Q1

    The devices have integrated an SAR ADC for diagnostics. It can monitor voltage on SUPPLY and OUTx pins. The ADC coverage range of SUPPLY and OUTx voltage is up to 20V for TPS929120-Q1, and 40V for TPS929121-Q1.

    The internal ADC continuously monitors the supply voltage and compares the results with internal threshold V(ADCLOWSUPTH) set by CONF_ADCLOWSUPTH. Since the ADC coverage range of TPS929120-Q1 and TPS929121-Q1 is different, the low-supply warning threshold set by CONF_ADCLOWSUPTH is also different. The threshold range of TPS929120-Q1 is 5-20V. And the threshold range of TPS929121-Q1 is 10-40V. The settings are shown below.

    TPS929120-Q1 low-supply warning threshold setting


    TPS929121-Q1 low-supply warning threshold setting


    The low-supply warning is used to disable the LED open-circuit detection and single-LED short-circuit detection. When the voltage applied on SUPPLY pin is higher than the threshold V(ADCLOWSUPTH), the TPS929120/1-Q1 enables LED open-circuit and single-LED short-circuit diagnosis. When supply voltage is lower than the threshold V(ADCLOWSUPTH), the device disables LED-open-circuit detection and single-LED short-circuit diagnosis. For TPS929121-Q1, the low-supply warning range is 10-40V, so the LED open and single-LED short fault cannot be detected when supply voltage is lower than 10V.

    2. The difference between the A and non-A versions

    In short, the difference between TPS929120/1 and TPS929120/1(A) is the different default value of EEPROM register EEP_ADDR[3] .

    The devices has 3 pinouts including ADDR2, ADDR1 and ADDR0 for slave address configuration. There are additional 4-bit EEPROM register to program the slave address. The EEPROM register EEP_INTADDR determines whether the device slave address is set by address pins setup or internal EEPROM register code.

    If EEP_INTADDR is 1, the device uses the binary code burnt in EEPROM register EEP_DEVADDR as slave address, as shown in the table below.

    If EEP_INTADDR is 0 (default), the device uses EEP_DEVADDR[3] code together with external inputs on ADDR2, ADDR1 and ADDR0 as shown in the table and ignore EEP_DEVADDR[2:0] code.

    The TPS929120/1 has EEP_DEVADDR[3] bit set to 0 as default, however TPS929120/1A version has EEP_DEVADDR[3] bit set to 1 as default. It allows up to 16 pieces of TPS929120/1-Q1 on same FlexWire bus accessible through external configuration on ADDR2, ADDR1 and ADDR0 without burning the EEP_DEVADDR registers.

    Since the EEP_DEVADDR[3] default value in EEPROM is different, two other registers CALC_EEPCRC and EEP_CRC default values in the devices are also different.