AS8501 - Data Sheet

austriamicrosystems

Revision 1.1, 04-April-06

www.austriamicrosystems.com

Page 5 of 40

6

Electrical characteristics

VDDA=5V +/-0.1 V, fclk=8.192 MHz, chopping ratio MM=4 (see 7.5.3), oversampling frequency=2.048 MHz, oversampling ratio=128

temperature range : -40 to 125°C if not otherwise noted

symbol

parameter

conditions

min

typ

max

units

input characteristics

G1

for gain 1 the input signal is connected directly to th input of the converter, this is not possible for the RSHH-RSHL

input

Gain

gains of PGA

6, 24, 50, 100

1)

AC_g6

Accuracy at gain 6

0 to 85 °C

1.0

% @-120mV

2)

-40 to 125°C

1.5

% @-120mV

3),4)

AC_g24

Accuracy at gain 24

0 to 85 °C

0.5

0.08

% @+-20mV

2)

-40 to 125°C

1.5

0.3

% @+-20mV

3) 4)

AC_g50

Accuracy at gain 50

0 to 85 °C

1.0

% @+-10mV

4)

AC_g100

Accuracy at gain 100

0 to 85 °C

1.0

% @+-5mV

4)

Vin

input voltage ranges

G1

-350

-300 to + 800

900

mV

5) 6)

(with reference to RSHL)

G6

-200

+/- 120

160

mV

5) 7)

G24

-40

+/- 30

40

mV

5) 7)

G50

-20

+/- 15

20

mV

5) 8)

G100

-10

+/- 7.5

10

mV

5) 8)

Notes:

1)

the absolute gain values are subjected to a manufacturing spread of +/-30% max in the full temperature range. all gain values can be digitally

calibrated together with the external circuitry with a resolution better than 0.065%

2)

Current measurement paths for G6 and G24 are trimmed for minimum Temperature coefficient. The trimm algorithm is based on a 2 temperature

measurement at 23°C and 60°C.

Accuracy is mainly determined by bandgap characteristic and gain variation over temperature.

A TC shift of typically -15 ppm/K will occure during solder process which is compensated by a systematic offset during trimming.

3)

due to a nonlinear behaviour of the gain and reference voltage over temperature the accuracy is lower for the extended temperature range.

4)

The minimum limits for G50, G100 are derived from device characterization and not tested. Towards 125°C the TC values are higher.

therefore it is recommended to use these gain settings only for applications in the temperature range 0 to 85°C.

5)

if not otherwise specified the ranges are calibrated to the typical values. The maximum and minimum value represent the maximum usable span

accepting linearity deviation up to 1000 digits. Min, max limits are tested at room temperature only!

6)

this gain range is not using the internal PGA, the input is directely connected to the AD-converter. Therefore the input resistance is lower then for

other gain ranges.

It has been designed mainly for positive input voltages up to 0.8 V i.e. for measurements of temperature with transistors and diodes.

The limitation for negative input voltages is due to the onset of conduction of the input protection diodes.

7)

the ASSP is optimised for G6 and G24 concerning linearity, speed and TC, therefore these ranges are recommended whenever possible.

8)

because of higher TC value at elevated temperature G50 and G100 are recommended for applications in the temperature range 0 to 85°C