CS5524 View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS5524

16-bit or 24-bit, 2/4/8-channel ADCs with PGIA

Cirrus Logic 

CS5521/22/23/24/28

offset to occur in the 25 mV, 55 mV, and 100 mV

ranges, the AIN- pin must be at the proper com-

mon-mode voltage as specified in ‘Common Mode

+Signal AIN+/-’ specification in the Analog Input

section (if AIN- = 0 V, NBV must be between -

1.8 V to -2.5 V). For self calibration of offset in the

1.0 V, 2.5 V, and 5 V ranges, the inputs of the mod-

ulator are connected together and then routed to the

VREF- pin as shown in Figure 12.

For self calibration of gain, the differential inputs

of the modulator are connected to VREF+ and

VREF- as shown in Figure 13. For any input range

other than the 2.5 V range, the converter’s gain er-

ror can not be completely calibrated out when using

self calibration. This is due to the lack of an accu-

rate full-scale voltage internal to the chips. The

2.5 V range is an exception because the external

reference voltage is 2.5 V nominal and is used as

the full-scale voltage. In addition, when self cali-

bration of gain is performed in the 25 mV, 55 mV,

and 100 mV input ranges, the instrumentation am-

plifier’s gain is not calibrated. These two factors

can leave the converters with a gain error of up to

±20% after self calibration of gain. Therefore, a

system gain calibration is required to get better ac-

curacy, except for the 2.5 V range.

1.3.2 System Calibration

For the system calibration functions, the user must

supply the calibration signals to the converter which

represent ground and full scale. When a system offset

calibration is performed, a ground-referenced signal

must be applied to the converters. See

Figures 14 and 15.

As shown in Figures 16 and 17, the user must input

a signal representing the positive full-scale point to

S1

OPEN

AIN+

+

+

S2

X20

CLOSED

AIN-

-

-

Figure 11. Self Calibration of Offset (Low Ranges)

AIN+

AIN-

VREF-

S1

OPEN

+

+

X20

-

-

S2

OPEN

S4

CLOSED

Figure 12. Self Calibration of Offset (High Ranges)

AIN+

AIN-

VREF+

Reference +- VREF-

OPEN

+

+

X20

-

-

OPEN

CLOSED

CLOSED

Figure 13. Self Calibration of Gain (All Ranges)

32

External

Connections

+

+

AIN+

0V +-

X20

-

-

CM +-

AIN-

Figure 14. System Calibration of Offset (Low Ranges)

DS317F6

Share Link: