adc1215s125hn/c1 NXP Semiconductors, adc1215s125hn/c1 Datasheet - Page 19

• Manufacturer Part Number: adc1215s125hn/c1
• Description: Single 12-bit Adc; 65 Msps, 80 Msps, 105 Msps Or 125 Msps With Input Buffer; Cmos Or Lvds Ddr Digital Outputs
• Manufacturer: NXP Semiconductors

NXP Semiconductors
ADC1215S_SER_1
Preliminary data sheet
11.3.1 Internal/external references
11.3 System reference and power management
The ADC1215S has a stable and accurate built-in internal reference voltage to adjust the
ADC full-scale. This reference voltage can be set internally via SPI or with pins VREF and
SENSE (programmable in 1 dB steps between 0 dB and −6 dB via control bits
INTREF[2:0] when bit INTREF_EN = 1; see
Figure 14
reference is also possible by providing a voltage on pin VREF as described in
If bit INTREF_EN is set to 0, the reference voltage will be determined either internally or
externally as detailed in
Table 11.
[1]
Selection
internal
(Figure
internal
(Figure
external
(Figure
internal via SPI
(Figure
Fig 11. Reference equivalent schematic
The voltage on pin VREF is doubled internally to generate the internal reference voltage.
SENSE
VREF
12)
13)
14)
15)
and
Reference selection
Figure
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SPI bit
INTREF_EN
0
0
0
1
ADC1215S series; input buffer; CMOS or LVDS DDR digital output
BUFFER
SELECTION
15. The equivalent reference circuit is shown in
LOGIC
Rev. 01 — 12 April 2010
Table
11.
SENSE pin
AGND
pin VREF connected to pin SENSE and
via a 330 pF capacitor to AGND
V
pin VREF connected to pin SENSE and
via 330 pF capacitor to AGND
REFERENCE
DDA(3V)
AMP
EXT_ref
EXT_ref
Table
VREF pin
330 pF capacitor to AGND
external voltage between
0.5 V and 1 V
REFERENCE
BANDGAP
21). See
ADC1215S series
[1]
Figure
ADC CORE
12,
Figure
REFT
REFB
Figure
© NXP B.V. 2010. All rights reserved.
full scale (p-p)
1 V
1 V to 2 V
1 V to 2 V
2 V
11. External
13,
Figure
19 of 39
14.