adc081c027cimkx National Semiconductor Corporation, adc081c027cimkx Datasheet - Page 21

• Manufacturer Part Number: adc081c027cimkx
• Description: I2c-compatible, 12-bit Analog-to-digital Converter Adc With Alert Function
• Manufacturer: National Semiconductor Corporation

1.7.4 I
The ADC has a seven-bit hardware address which is also referred to as a slave address. For the MSOP-8 version of the AD-
C081C021, this address is configured by the ADR0 and ADR1 addres selection inputs. For the ADC081C027, the address is
configured by the ADR0 address selection input. ADR0 and ADR1 can be grounded, left floating, or tied to V
can be set to V
I
1010100. The diagrams in Section 1.10 COMMUNICATING WITH THE ADC081C021 describe how the I
address the ADC via the I
Pin compatible alternatives that provide additional address options to the TSOT-6 version of the ADC081C021 and the AD-
C081C027 are available.
1.8 ALERT FUNCTION
The ALERT function is an "out-of-range" indicator. At the end
of every conversion, the measured voltage is compared to the
values in the V
age exceeds the value stored in V
stored in V
is indicated in up to three places. First, the alert condition al-
ways causes either or both of the alert flags in the Alert Status
register to go high. If the measured voltage exceeds the
V
voltage falls below the V
is set. Second, if the Alert Flag Enable bit is set in the Con-
figuration register, the alert condition also sets the MSB of the
Conversion Result register. Third, if the Alert Pin Enable bit is
set in the Configuration register, the ALERT output becomes
active (see Figure 9). The ALERT output (ADC081S021 only)
2
C bus (see Table 1). For the TSOT-6 version of the ADC081C021, the hardware address is not pin-configurable and is set to
HIGH
limit, the Over Range Alert Flag is set. If the measured
2
C Slave (Hardware) Address
LOW
Slave Address
, an alert condition occurs. The Alert condition
HIGH
A
/2 rather than left floating. The state of these inputs sets the hardware address that the ADC responds to on the
[A6 - A0]
1010000
1010001
1010010
1010100
1010101
1010110
1011000
1011001
1011010
and V
LOW
LOW
2
C interface.
limit, the Under Range Alert Flag
registers. If the measured volt-
HIGH
ADC081C027
or falls below the value
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
FIGURE 8. Beginning Hs-Mode Communication
(TSOT-6)
Floating
ADR0
GND
V
A
TABLE 1. Slave Addresses
Single Address
ADC081C021
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
(TSOT-6)
ALERT
21
can be configured as an active high or active low output via
the Polarity bit in the Configuration register. If the Polarity bit
is cleared, the ALERT output is configured as active low. If
the Polarity bit is set, the ALERT output is configured as active
high.
The Over Range Alert condition is cleared when one of the
following two conditions is met:
1.
2.
The controller writes a one to the Over Range Alert Flag
bit.
The measured voltage goes below the programmed
V
Alert Hold bit is cleared in the Configuration register. (see
Figure 9). If the Alert Hold bit is set, the alert condition
persists and only clears when a one is written to the Over
Range Alert Flag bit.
HIGH
limit minus the programmed V
Floating
Floating
Floating
ADR1
GND
GND
GND
V
V
V
A
A
A
ADC081C021
(MSOP-8)
Floating
Floating
Floating
ADR0
GND
GND
GND
V
V
V
A
A
A
2
HYST
C controller should
A
. If desired, ADR0
value and the
www.national.com
30052112