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AFE4490: Differences between AFE4400 and AFE4490

Takashi Matsumura
Prodigy 60 points
Part Number: AFE4490
Other Parts Discussed in Thread: AFE4400

Differences between AFE4400 and AFE4490
1.　TIAGAIN [D10: D0] in AFE4490 is a receiving circuit parameter of LED1 (IR).
TIA_AMB_GAIN [D10: D0] is a receiving circuit parameter of LED2 (RED).
TIA_AMB_GAIN [D10: D0] in AFE4400 is the receiving circuit parameters of LED1 (IR) and LED2 (RED).
LED1 (IR) and LED2 (RED) parameters in AFE4400
are not able to be set individually. Is this okay ?

2.　Are CF_LED1, CF_LED2, RFLED1, and RF_LED2 set CF and RF at Figure55. Receive Front-End ?
Figure55. Receive Front-End is in AFE4490 spcification sheet.

3.　Are STG2GAIN1(for LED1) and STG2GAIN2(for LED2) setting the RG of Stage2-Gain AMP in Figure 55.?

4.　When the bit of TIAGAIN_STAGE2EN1 in AFE4490 is "0",
is the STAGE2 of LED1 receiving circuit bypassed ?
When the bit of TIA_AMB_GAIN_STAGE2EN2 is "0",
is the STAGE2 of LED2 receiving circuit bypassed ?

  • 0
    TI__Mastermind 49186 points

    Hello,

    AFE4490 supports separate gain mode whereas AFE4400 does not.

    When ENSEPGAIN = 0, the RF, CF values and stage 2 gain settings are the same for both the LED2 and LED1 signals; the values are specified by the RF_LED2, CF_LED2, STAGE2EN2, and STG2GAIN2 bits in the TIA_AMB_GAIN register (default after reset)

    When ENSEPGAIN = 1, the RF, CF values and stage 2 gain settings can be independently set for the LED2 and LED1 signals. The values for LED1 are specified using the RF_LED1, CF_LED1, STAGE2EN1, and STG2GAIN1 bits in the TIAGAIN register, whereas the values for LED2 are specified using the corresponding bits in the TIA_AMB_GAIN register.

    Figure 55 does not explicitly depict the RF, CF and stage 2 gain settings for the separate gain mode.

    Regarding your questions 2,3,4, please refer to the explanation above for the separate gain mode.

    Hope this clarifies.