X96011_08 Datasheet, PDF (9/18 Pages) Intersil Corporation – Temperature Sensor with Look-Up Table Memory and DAC

X96011
Control Register 1
This register is accessed by performing a Read or Write
operation to address 81h of memory. This byte’s volatility is
determined by bit NV13 in Control register 0.
LDA5 - LDA0: LUT DIRECT ACCESS BITS
When bit LDAS (bit 4 in Control register 5) is set to “1”, the LUT
is addressed by these six bits, and it is not addressed by the
output of the on-chip A/D converter. When bit LDAS is set to
“0”, these six bits are ignored by the X96011. See Figure 7.
A value between 00h (00₁₀) and 3Fh (63₁₀) may be written to
these register bits, to select the corresponding row in the
LUT. The written value is added to the base address of the
LUT (90h).
Control Register 3
This register is accessed by performing a Read or Write
operation to address 83h of memory. This byte’s volatility is
determined by bit NV13 in Control register 0.
DDA7 - DDA0: D/A DIRECT ACCESS BITS
When bit DDAS (bit 5 in Control register 5) is set to “1”, the
input to the D/A converter is the content of bits DDA7-DDA0,
and it is not a row of LUT. When bit DDAS is set to “0” (default)
these eight bits are ignored by the X96011. See Figure 6.
Control Register 5
This register is accessed by performing a Read or Write
operation to address 85h of memory.
IFSO1 - IFSO0: CURRENT GENERATOR FULL SCALE
OUTPUT SET BITS (NON-VOLATILE)
These two bits are used to set the full scale output current at
the Current Generator pin, Iout, according to the following
table. The direction of this current is set by bit IDS in Control
register 0. See Figure 5.
I1FSO1
0
0
1
1
I1FSO0
0
1
0
1
I1 Full Scale Output Current
Reserved (Don’t Use)
±0.4mA
±0.85 mA
±1.3 mA (Default)
LDAS: LUT DIRECT ACCESS SELECT BIT
(NON-VOLATILE)
When bit LDAS is set to “0” (default), the LUT is addressed
by the output of the on-chip A/D converter. When bit LDAS is
set to “1”, LUT is addressed by bits LDA5 - LDA0.
DDAS: D/A DIRECT ACCESS SELECT BIT
(NON-VOLATILE)
When bit DDAS is set to “0” (default), the input to the D/A
converter is a row of the LUT. When bit DDAS is set to “1”,
that input is the content of the Control register 3.
Control Register 6
This register is accessed by performing a Read or Write
operation to address 86h of memory.
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). Otherwise, 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 operation 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 output 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 I_OUT.
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. Alternatively, 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 current
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 output current pin (I_OUT) via a
“polarity select” circuit block.
9
FN8215.2
February 25, 2008