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ADS-117

12-Bit, 2MHz, Low-Power Sampling A/D Converters

Murata Power Solutions 

ADS-117

12-Bit, 2MHz, Low-Power Sampling A/D Converters

CALIBRATION PROCEDURE

1. Connect the converter per Figure 3, Figure 4, and Table 1 for the ap-

propriate input range. Apply a pulse of 150 nanoseconds to the START

CONVERT input (pin 16) at a rate of 250kHz. This rate is chosen to

reduce flicker if LED’s are used on the outputs for calibration purposes.

2. Zero Adjustments

Apply a precision voltage reference source between the amplifier’s

analog input and ground. Adjust the output of the reference source per

Table 2. For unipolar, adjust the zero trimming potentiometer so that

the output code flickers equally between 0000 0000 0000 and 0000

0000 0001 with the pin 18 tied high (straight binary) or between 1111

1111 1111 and 1111 1111 1110 with the pin 18 tied low (complemen-

tary binary).

For bipolar operation, adjust the potentiometer such that the code flick-

ers equally between 1000 0000 0000 and 1000 0000 0001 with pin 18

tied high (offset binary) or between 0111 1111 1111 and 0111 1111

1110 with pin 18 tied low (complementary offset binary).

3. Full-Scale Adjustment

Set the output of the voltage reference used in step 2 to the value

shown in Table 1. Adjust the gain trimming potentiometer so that the

output code flickers equally between 1111 1111 1110 and 1111 1111

1111 for pin 18 tied high or between 0000 0000 0001 and 0000 0000

0000 for pin 18 tied low.

4. To confirm proper operation of the device, vary the precision reference

voltage source to obtain the output coding listed in Table 3.

R2 ➀

R1➀

SIGNAL

INPUT

5kΩ

50Ω

GAIN

ADJUST

+15V

–15V

To Pin19

of ADS-117

5kΩ

10kΩ

ZERO/

OFFSET

ADJUST

➀ For values of R1 and R2 refer to Table 1.

Figure 4. Optional Calibration Circuit

Table 1. Input Connections (using external calibration)

INPUT RANGE

R1

R2

UNIT

0 +10V, ±5

2

2

kΩ

0 to 5V, ±2.5V

2

6

kΩ

0 to +2.5V, ±1.25V

2

14

kΩ

Table 2. Zero and Gain Adjustments

INPUT RANGE

ZERO ADJUST

+1/2 LSB

GAIN ADJUST

RANGE

0 to +10V

+1.22mV

+9.9963V

±5V

+1.22mV

+4.9963V

UNIPOLAR

OPERATION

20 BIPOLAR INPUT

+

0.1μF 4.7μF

21 +10V REF.

–15V

24

4.7μF

+

0.1μF

23

4.7μF

+15V

+ 0.1μF

22

+5V

13

+

4.7μF

0.1μF

14

ADS-117

COMP BIN 18

12 BIT 1 (MSB)

11 BIT 2

10 BIT 3

9 BIT 4

8 BIT 5

7 BIT 6

6 BIT 7

5 BIT 8

4 BIT 9

3 BIT 10

2 BIT 11

1 BIT 12 (LSB)

15 EOC

17 ENABLE (1-12)

16 START CONVERT

19 ANALOG INPUT

+5V

NOTE: For unipolar operation, ground pin 20.

For bipolar operation, connect pin 20 to pin 21.

Always bypass pin 21 as shown for both unipolar

and bipolar operation.

Figure 3. ADS-117 Connection Diagram

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Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000

MDA_ADS-117.B01 Page 4 of 6

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