Datasheet

AFE5808
www.ti.com SLOS688C –SEPTEMBER 2010–REVISED APRIL 2012
VCA Register Map
Table 4. VCA Register Map
ADDRESS ADDRESS Default
FUNCTION DESCRIPTION
(DEC) (HEX) Value
51[0] 0x33[0] 0 RESERVED 0
51[3:1] 0x33[3:1] 0 LPF_PROGRAMMABILITY 000: 15MHz,
010: 20MHz,
011: 30MHz,
100: 10MHz
51[4] 0x33[4] 0 PGA_INTEGRATOR_DISABLE 0: Enable
(PGA_HPF_DISABLE)
1: Disables offset integrator for PGA. Please see explanation
for the PGA integrator function in APPLICATION
INFORMATION section
51[6:5] 0x33[6:5] 0 PGA_CLAMP_LEVEL 00: –2dBFS;
10: 0dBFS;
01:–4dBFS when 51[7]=0
Note: the clamp circuit makes sure that PGA output is in linear
range. For example, at 00 setting, PGA output HD3 will be
worsen by 3dB at –2dBFS ADC input. In normal operation,
clamp function can be set as 00
51[7] 0x33[7] 0 PGA_CLAMP_DISABLE 0:Enables the PGA clamp circuit;
1:Disables the PGA clamp circuit at PGA outputs. 51[6:5]
determines the clamp output level
51[13] 0x33[13] 0 PGA_GAIN_CONTROL 0:24dB;
1:30dB
52[4:0] 0x34[4:0] 0 ACTIVE_TERMINATION_ SeeTable 6 Reg 52[5] should be set as '1' to access these bits
INDIVIDUAL_RESISTOR_CNTL
52[5] 0x34[5] 0 ACTIVE_TERMINATION_ 0: Disables;
INDIVIDUAL_RESISTOR_ENABLE
1: Enables internal active termination individual resistor control
52[7:6] 0x34[7:6] 0 PRESET_ACTIVE_ TERMINATIONS 00: 50Ω,
01: 100Ω,
10: 200Ω,
11: 400Ω
(Note: the device will adjust resistor mapping (52[4:0])
automatically. 50ohm active termination is NOT supported in
12dB LNA setting. Instead, '00' represents high impedance
mode when LNA gain is 12dB)
52[8] 0x34[8] 0 ACTIVE TERMINATION ENABLE 0: Disables;
1: Enables active termination
52[10:9] 0x34[10:9] 0 LNA_INPUT_CLAMP_SETTING 00: Auto setting (Recommended for most cases. Clamp level
can be set automatically depending LNA gain. 350mVpp when
LNA = 24dB, 600mVpp when LNA = 18dB, 1.15Vpp when
LNA = 12dB)
01: 1.5Vpp,
10: 1.15Vpp,
11: 0.6Vpp
52[11] 0x34[11] 0 RESERVED Set to 0
52[12] 0x34[12] 0 LNA_INTEGRATOR_DISABLE 0: Enables;
(LNA_HPF_DISABLE)
1: Disables offset integrator for LNA. Please see the
explanation for this function in the following section
52[14:13] 0x34[14:1 0 LNA_GAIN 00: 18dB;
3]
01: 24dB;
10: 12dB;
11: Reserved
52[15] 0x34[15] 0 LNA_INDIVIDUAL_CH_CNTL 0: Disable;
1: Enable LNA individual channel control. See Register 57 for
details
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