Datasheet

REV. 0
AD1871
–23–
Single-Ended Mode Enable
The Single-Ended Mode Enable Bits (SEL and SER for left and
right channels, respectively), when set to 1, are used to configure
single-ended input on VINxP and VINxN (input is selected by
state of MXL and MXR). In this mode, single-ended inputs taken
from either VINxP or VINxN (selected using the Mux Select
Bits—MXL and MXR) are internally converted to a differential
format to be applied to the modulator section (see Table XII).
Table XII. Differential/Single-Ended Select
SEL SER Input Setting
0X
Left Channel Input Æ Differential
1X
Left Channel Input Æ Single-Ended
X0
Right Channel Input Æ Differential
X1 Right Channel Input Æ Single-Ended
Master Clock Divider
The master clock divider allows the division of the external
MCLK frequency to a more suitable internal master clock
frequency (IMCLK). IMCLK must be 256 ¥ f
S
; therefore, if
the available MCLK is not at 256 ¥ f
S
but is a multiple of
this, the MCD allows conversion of MCLK to a suitable IMCLK
at 256 ¥ f
S
(see Table XIII).
Table XIII. Master Clock Divider Settings
MCD1 MCD0 MCLK Division
00IMCLK = MCLK (/1)
01IMCLK = MCLK/2
10IMCLK = MCLK/3
11IMCLK = MCLK (/1)
Table IX. Control Register III (Address 0010b)
15–12 11 10 9 8 7 6 5 4 3 2 1 0
0010 0 0 MCD1 MCD0 SEL SER MEL MXL MER MXR
9–8 Reserved (Should Be Programmed to 0)
7–6 MCD1–MCD0 Master Clock Divider (See Table XIII)
5 SEL Single-Ended Enable, Left Channel (0 = Differential
(Default) ; 1 = Single-Ended)
4 SER Single-Ended Enable, Right Channel (0 = Differential
(Default) ; 1 = Single-Ended)
3 MEL Mux/PGA Disable, Left Channel (0 = Enabled
(Default) ; 1 = Disabled)
2 MXL Mux Select, Left Channel (0 = VINLP Selected
(Default) ; 1 = VINLN Selected)
1 MER Mux/PGA Disable, Right Channel (0 = Enabled
(Default) ; 1 = Disabled)
0 MXR Mux Select, Right Channel (0 = VINRP Selected (Default) ; 1 = VINRN Selected)
Control Register III
Control Register III contains bit settings for configuration of the
analog input section (both left and right channels).
Mux Enable
The Mux Enable Left (MEL) and Mux Enable Right (MER)
are used to enable the analog buffers. When these bits are set to
1, the analog input buffers are powered down and input signals
must be applied directly to the modulator inputs via the CAPxP
and CAPxN pins. (see Figure 23). When MEL and MER are set
to 0 (default condition after reset), the analog input section is
enabled, (see Table X).
Table X. Mux Control Settings
MEL MER Input Setting
0X
Left Channel Analog Buffer Enabled
1X
Left Channel Analog Buffer Disabled
X0
Right Channel Analog Buffer Enabled
X1 Right Channel Analog Buffer Disabled
Mux Select
The Mux Select Bits (MXL and MXR for left and right channels,
respectively) are used to select the input from VINxP or VINxN
when the input is configured as single-ended. When MXx is set
to 0, the input is taken from VINxP. When MXx is set to 1, the
input is taken from VINxN, (see Table XI).
Table XI. Mux Select Settings*
MXL MXR Input Setting
0X
Left Channel Input from VINLP
1X
Left Channel Input from VINLN
X0
Right Channel Input from VINRP
X1 Right Channel Input from VINRN
*Mux select settings are only valid when single-ended operation is enabled; SEL
and SER are set to 1.