AS8500 - Data Sheet

austriamicrosystems

Revision 1.2, 08-Junel-06

www.austriamicrosystems.com

Page 5 of 41

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

0.4

% @-120mV

2)

-40 to 125°C

1.0

% @-120mV

2),3)

AC_g24

Accuracy at gain 24

0 to 85 °C

0.2

% @+-20mV

2)

-40 to 125°C

0.6

% @+-20mV

2) 3)

AC_g50

Accuracy at gain 50

0 to 85 °C

1

% @+-10mV

2)4)

AC_g100

Accuracy at gain 100

0 to 85 °C

1

% @+-5mV

2)4)

Vin

input voltage ranges

G1

-300 to + 800

mV

5)

(with reference to RSHL)

G6

+/- 120

mV

6)

G24

+/- 30

mV

6)

G50

+/- 15

mV

7)

G100

+/- 7.5

mV

7)

Notes:

1)

the absolute gain values are subjected to a manufacturing spread of +/-30%

2)

Accuracy relies on bandgap characteristic, on the gain variation over temperature and on the trimm information. To achieve optimum performance,

the circuit may be trimmed by the user for best temperature stability by writting aproporiate data to the TRR register (see sections 7.4 and 7.5)

Default content of TRR register is 17.

3)

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

4)

It is recommended to use these gain settings only for applications in the temperature range 0 t0 85°C

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

5)

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.

6)

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

7

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