X96011 Datasheet, PDF (13/23 Pages) Intersil Corporation – Temperature Sensor with Look Up Table Memory and DAC

X96011
WEL: WRITE ENABLE LATCH (VOLATILE)
The WEL bit controls the Write Enable status of the
entire X96011 device. This bit must be set to “1” before
any other Write operation (volatile or nonvolatile). Oth-
erwise, any proceeding Write operation to memory is
aborted and no ACK is issued after a Data Byte.
The WEL bit is a volatile latch that powers up in the “0”
state (disabled). The WEL bit is enabled by writing
10000000₂ to Control register 6. Once enabled, the
WEL bit remains set to “1” until the X96011 is powered
down, and then up again, or until it is reset to “0” by
writing 00000000₂ to Control register 6.
A Write operation that modifies the value of the WEL bit
will not cause a change in other bits of Control register 6.
Status Register - ADC Output
This register is accessed by performing a Read opera-
tion to address 87h of memory.
AD7 - AD0: A/D CONVERTER OUTPUT BITS (READ ONLY)
This byte is the binary output of the on-chip digital
thermometer. The output is 00000000₂ for -40°C and
11111111₂ for 100°C. The six MSBs select a row of
the LUT.
LOOK-UP TABLE
The X96011 memory array contains a 64-byte look-up
table. The look-up table is associated to pin Iout’s out-
put current generator through the D/A converter. The
output of the look-up table is the byte contained in the
selected row. By default this byte is the input to the
D/A converter driving pin Iout.
The byte address of the selected row is obtained by
adding the look-up table base address 90h, and the
appropriate row selection bits. See Figure 6.
By default the look-up table selection bits are the
6 MSBs of the digital thermometer output. Alter-
natively, the A/D converter can be bypassed and the
six row selection bits are the six LSBs of Control
Register 1 for the LUT. The selection between these
options is illustrated in Figure 6.
CURRENT GENERATOR BLOCK
The Current Generator pin Iout is the output of the cur-
rent mode D/A converter.
D/A Converter Operation
The Block Diagram for the D/A converter is shown in
Figure 5.
The input byte of the D/A converter selects a voltage
on the non-inverting input of an operational amplifier.
The output of the amplifier drives the gate of a FET.
This node is also fed back to the inverting input of the
amplifier. The drain of the FET is connected to the out-
put current pin (Iout) via a “polarity select” circuit block.
13
FN8215.1
October 25, 2005