AS8501 - Data Sheet

austriamicrosystems

Revision 1.1, 04-April-06

www.austriamicrosystems.com

Page 19 of 40

subregister MM: chopping ratio bit, Registers CRA, CRB

Nr.

MM

mm

NOTE

0

4

0

1

8

1

2

1

Notes:

1) For c=0 and d=0 , chopping and dechopping is switched off and every cycle is active regardless

of mm, i.e. the sampling frequenzy is higher by a factor of 4

subregister CRN: averaging bits ( 4 bits), registers CRA,CRB

Nr.

R2

n3

n2

n1

n0

NOTE

0

1

0

0

0

0

1

2

0

0

0

1

2

4

0

0

1

0

3

8

0

0

1

1

4

16

0

1

0

0

5

32

0

1

0

1

6

64

0

1

1

0

7

128

0

1

1

1

8

256

1

0

0

0

9

512

1

0

0

1

10

1024

1

0

1

0

11-14

Reserved for test

1

x

x

15

raw mode

1

1

1

Note:

1)

combinations from B to E are reserved for test

2)

this mode delivers the AD-values without calibration and averaging but multiplied by a factor which is dependent on the

setting of the oversampling ratio. It can be used for high resolution measurements of very low signals since it eliminates

the internal rounding error.

The ratio between raw result (Nr) and normal result (Nn) is given by: Nr/Nn = 2^(11+x)/CAL where x=6 for R=128 and x=3

for R=64. CAL is the calibration constant used.

7.5.4

CRB measurement channel B configuration register ( 17 bits )

Nr.

Bits

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

NOTE

0

CRB bit

names

cu2 cu1 cu0 M5

M4

M3

M2

M1

g1

g0

f

r

mm

n3

n2

n1

1

Defaults

0

0

0

0

1

1

0

0

0

1

1

0

0

0

0

0

2

subreg.

CRU

CRM

GN

OSF

OSR

MM

CRN

Notes:

1)

This register defines the measurement channel B configuration, the functions of the subregisters are the same as

described above for measurement channel A

2)

Default power-up state before any setting

3)

In this mode the chip cannot measure the current sensing input RSHH-RSHL, therefore M1=0 for all settings