X96011 Datasheet, PDF (15/23 Pages) Intersil Corporation – Temperature Sensor with Look Up Table Memory and DAC

X96011
By examining the block diagram in Figure 5, we see
that the maximum current through pin Iout is set by fix-
ing values for V(VRef) and R. The output current can
then be varied by changing the data byte at the D/A
converter input.
In general, the magnitude of the current at the D/A
converter output pin may be calculated by:
I = (V(VRef) / (384 • R)) • N
where N is the decimal representation of the input byte
to the corresponding D/A converter.
The value for the resistor determines the full scale out-
put current that the D/A converter may sink or source.
Bits IFSO1 and IFSO0 select the full scale output cur-
rent setting for Iout as described in “IFSO1 - IFSO0:
Current Generator Full Scale Output Set Bits (Non-vol-
atile)” on page 12.
Bit IDS and in Control Register 0 select the direction of
the currents through pins Iout (See “IDS: Current Gen-
erator Direction Select Bit (Non-volatile)” on page 10
and “Control and Status Register Format” on
page 11).
D/A Converter Output Current Response
When the D/A converter input data byte changes by
an arbitrary number of bits, the output current changes
from an intial current level (I_x) to some final level
(I_x + ∆I_x). The transition is monotonic and glitchless.
D/A Converter Control
The data byte inputs of the D/A converters can be con-
trolled in three ways:
– 1) With the A/D converter and through the look-up
tables (default),
– 2) Bypassing the A/D converter and directly access-
ing the look-up tables,
– 3) Bypassing both the A/D converter and look-up
tables, and directly setting the D/A converter input
byte.
Figure 7. Look-Up Table Addressing
Voltage
Reference
Voltage Input
from Internal
temperature
sensor
ADC
6
8
AD[7:0]
Status
Register
LDA[5:0]:
Control
6
D1
Register 1
Out
D0
Select
LUT Row
Selection bits
LDAS: bit 4 in
Control register 5
15
FN8215.1
October 25, 2005