Datasheet

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SLIS110A − APRIL 2003 − REVISED MAY 2005
12
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PRINCIPLES OF OPERATION
system transfer equation
The output voltage may be derived from:
V
O
+ V
IN
A
IN
A
P
A
BP
A
INT
t
INT
t
C
A
O
) V
RESET
where:
V
IN
= Input voltage peak (amplitude)
V
O
= Output voltage
A
IN
= Input amplifier gain setting
A
P
= Programmable gain setting
A
BP
= Gain of band-pass filter
A
INT
= Gain of integrator
t
INT
= Integration time from 0.5 ms to 10 ms
A
O
= Output buffer gain
τ
C
= Programmable integrator time constant
V
RESET
= Reset voltage from which the integration operation starts
If A
BP
= A
INT
= 2 and A
IN
= A
O
= 1,
then
V
O
+ V
IN
A
P
8
P
t
INT
t
C
) V
RESET
programming in normal mode (TEST = 1)
To enable programming in the normal mode, the TEST terminal must be high. Communication is through the
SPI and the CS
terminal is used to enable the IC. The information on the SDI line consists of two parts: address
and data.
After power up, the SPI is in default mode (see Table 2).
default SPI mode
The SPI is in the default mode on the power up sequence. In this case, the SDO directly equals the SDI (echo
function). In this mode, five commands can be transmitted by the master controller to configure the IC (see
Table 2).