X96012_08 Datasheet, PDF (16/23 Pages) Intersil Corporation – Universal Sensor Conditioner with Dual Look-up Table Memory and DACs

VOLTAGE
V_ADCOK
X96012
VCC
0V
CURRENT
ADC TIME
TIME
I_X
I_X X 10%
FIGURE 11. D/A CONVERTER POWER-ON RESET RESPONSE
TIME
VOLTAGE
REFERENCE
VOLTAGE INPUT
ADC
6
8
AD[7:0]
STATUS
REGISTER
L2DA[5:0]:
CONTROL
REGISTER 2
D1
OUT
D0
SELECT
LUT2 ROW
SELECTION BITS
L2DAS: BIT 6 IN
CONTROL REGISTER 5
L1DA[5:0]: ₆
CONTROL
D1
REGISTER 1
OUT
D0
SELECT
LUT1 ROW
SELECTION BITS
L1DAS: BIT 4 IN
CONTROL REGISTER 5
FIGURE 10. LOOK-UP TABLE ADDRESSING
The A/D converter is shared between the two current
generators but the look-up tables, D/A converters, control
bits, and selection bits can be set completely independently.
Bits D1DAS and D2DAS are used to bypass the A/D
converter and look-up tables, allowing direct access to the
inputs of the D/A converters with the bytes in control
registers 3 and 4 respectively. See Figure 9 and the
descriptions of the control bits starting on page 9.
Bits I1DS and I2DS in Control Register 0 select the direction
of the currents through pins I1 and I2 independently See
Figure 8 and the descriptions of the control bits starting on
page 9.
Power-on Reset
When power is applied to the V_CC pin of the X96012, the
device undergoes a strict sequence of events before the
current outputs of the D/A converters are enabled.
When the voltage at V_CC becomes larger than the power-on
reset threshold voltage (V_POR), the device recalls all control
bits from non-volatile memory into volatile registers. Next,
the analog circuits are powered up. When the voltage at Vcc
becomes larger than a second voltage threshold (V_ADCOK),
the ADC is enabled. In the default case, after the ADC
performs four consecutive conversions with the same exact
result, the ADC output is used to select a byte from each
look-up table. Those bytes become the input of the DACs.
16
FN8216.3
February 20, 2008