Datasheet

IN1
IN2
MICROPROCESSOR
DSP
SCLK
CS
DIN
DOUT
GND
V
A
ADC124S051
LP2950
5V
1 PF
TANT
0.1 PF 0.1 PF1 PF
IN3
IN4
| |
|
0V
+V
A
- 1.5LSB
0.5LSB
ANALOG INPUT
1LSB = V
A
/4096
ADC CODE
111...111
111...110
111...000
011...111
000...010
000...001
000...000
ADC124S051
www.ti.com SNAS260E –NOVEMBER 2004–REVISED NOVEMBER 2004
ADC124S051 TRANSFER FUNCTION
The output format of the ADC124S051 is straight binary. Code transitions occur midway between successive
integer LSB values. The LSB width for the ADC124S051 is V
A
/4096. The ideal transfer characteristic is shown in
Figure 49. The transition from an output code of 0000 0000 0000 to a code of 0000 0000 0001 is at 1/2 LSB, or a
voltage of V
A
/8192. Other code transitions occur at steps of one LSB.
Figure 49. Ideal Transfer Characteristic
TYPICAL APPLICATION CIRCUIT
A typical application of the ADC124S051 is shown in Figure 50. Power is provided, in this example, by the
LP2950 low-dropout voltage regulator, available in a variety of fixed and adjustable output voltages. The power
supply pin is bypassed with a capacitor network located close to the ADC124S051.
Because the reference for the ADC124S051 is the supply voltage, any noise on the supply will degrade device
noise performance. To keep noise off the supply, use a dedicated linear regulator for this device, or provide
sufficient decoupling from other circuitry to keep noise off the ADC124S051 supply pin. Because of the
ADC124S051's low power requirements, it is also possible to use a precision reference as a power supply to
maximize performance. The four-wire interface is shown connected to a microprocessor or DSP.
Figure 50. Typical Application Circuit
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