Datasheet
AFE4490
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SBAS602F –DECEMBER 2012–REVISED OCTOBER 2013
CONTROL2: Control Register 2 (Address = 23h, Reset Value = 0000h)
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12
RST_
CLK_ON EN_ADC
0 0 0 0 0 TX_REF1 TX_REF0 0 0 0
_PD_ _BYP
ALM
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
DIGOUT_ EN_
TXBRG XTAL
TRI SLOW_ 0 0 0 0 0 PDNTX PDNRX PDNAFE
MOD DIS
STATE DIAG
This register controls the LED transmitter, crystal, and the AFE, transmitter, and receiver power modes.
Bits D[23:19] Must be '0'
Bits D[18:17] TX_REF[1:0]: Tx reference voltage
These bits set the transmitter reference voltage. This Tx reference voltage is available on
the device TX_REF pin.
00 = 0.75-V Tx reference voltage (default value after reset)
01 = 0.5-V Tx reference voltage
10 = 1.0-V Tx reference voltage
11 = 0.75-V Tx reference voltage
NOTE: For best results, use TX_REF = 0.5 V for 3-V operation. Use TX_REF = 0.75V and
TX_REF = 1.0 V for 5-V operation.
Bit D16 RST_CLK_ON_PD_ALM: Reset clock onto PD_ALM pin
0 = Normal mode; no reset clock signal is connected to the PD_ALM pin
1 = Reset clock signal is connected to the PD_ALM pin
Bit D15 EN_ADC_BYP: ADC bypass mode enable
0 = Normal mode, the internal ADC is active (default after reset)
1 = ADC bypass mode, the analog signal is output to the ADC_BYPP and ADC_BYPN pins
Bits D[14:12] Must be '0'
Bit D11 TXBRGMOD: Tx bridge mode
0 = LED driver is configured as an H-bridge (default after reset)
1 = LED driver is configured as a push-pull
Bit D10 DIGOUT_TRISTATE: Digital output 3-state mode
This bit determines the state of the device digital output pins, including the clock output pin
and SPI output pins. In order to avoid loading the SPI bus when multiple devices are
connected, this bit must be set to '1' (3-state mode) whenever the device SPI is inactive.
0 = Normal operation (default)
1 = 3-state mode
Bit D9 XTALDIS: Crystal disable mode
0 = The crystal module is enabled; the 8-MHz crystal must be connected to the XIN and
XOUT pins
1 = The crystal module is disabled; an external 8-MHz clock must be applied to the XIN pin
Bit D8 EN_SLOW_DIAG: Fast diagnostics mode enable
0 = Fast diagnostics mode, 8 ms (default value after reset)
1 = Slow diagnostics mode, 16 ms
Bits D[7:3] Must be '0'
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