Datasheet

AFE4490
SBAS602F –DECEMBER 2012–REVISED OCTOBER 2013 www.ti.com
SPARE1: SPARE1 Register For Future Use (Address = 1Fh, Reset Value = 0000h)
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12
0 0 0 0 0 0 0 0 0 0 0 0
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 0 0 0 0 0 0 0 0 0
This register is a spare register and is reserved for future use.
Bits D[23:0] Must be '0'
TIAGAIN: Transimpedance Amplifier Gain Setting Register (Address = 20h, Reset Value = 0000h)
D23 D22 D21 D20 D19 D18 D17 D16 D15 D14 D13 D12
ENSEP
0 0 0 0 0 0 0 0 0 0 0
GAIN
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 0 CF_LED1[4:0] RF_LED1[2:0]
This register sets the device transimpedance amplifier gain mode and feedback resistor and capacitor values.
Bits D[23:16] Must be '0'
Bit D15 ENSEPGAIN: Enable separate gain mode
0 = The R
F
and C
F
values are the same for both LED2 and LED1 signals; the value specified
by the RF_LED2[2:0] register bits is used (default after reset)
1 = The R
F
value is different for the LED2 and LED1 signals; the values are specified by the
RF_LED1[2:0] and RF_LED2[2:0] register bits
Bits D[14:8] Must be '0'
Bits D[7:3] CF_LED1[4:0]: Program C
F
for LED1
00000 = 5 pF (default after reset) 00100 = 25 pF + 5 pF
00001 = 5 pF + 5 pF 01000 = 50 pF + 5 pF
00010 = 15 pF + 5 pF 10000 = 150 pF + 5 pF
Note that any combination of these C
F
settings is also supported by setting multiple bits to
'1'. For example, to obtain C
F
= 100 pF, set D[7:3] = 01111.
Bits D[2:0] RF_LED1[2:0]: Program R
F
for LED1
000 = 500 kΩ (default after reset) 100 = 25 kΩ
001 = 250 kΩ 101 = 10 kΩ
010 = 100 kΩ 110 = 1 MΩ
011 = 50 kΩ 111 = None
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