AMC7823 Datasheet, PDF (44/48 Pages) Texas Instruments – ANALOG MONITORING AND CONTROL CIRCUIT

AMC7823
SLAS453A – APRIL 2005 – REVISED OCTOBER 2005
www.ti.com
To avoid loss of alarm information in bits IOST-n during power-down of the ADC, change to direct conversion
mode (see ADC Control Register) before power-down and do not issue a convert command while the ADC is
powered down.
NOTE: When GPIO-n works as a general-purpose I/O pin, bit IOST-n does not change during the power-down
procedure.
After power-on or reset, all bits in the GPIO Register are set to '1'. All GPIO pins are configured as general I/O
pins and are in high-impedance state.
THRESHOLD REGISTERS
Threshold-Hi-n and Threshold-Low-n (n = 0, 1, 2, 3) define the upper bound and lower bound of the nth analog
input range. (See Table 2.) This window determines whether the nth input is out-of-range. When the input is
outside the window, the corresponding bit ALR-n in the ALR Register is set to '1'.
For normal operation, the value of Threshold-Hi-n must be greater than the value of Threshold-Low-n; otherwise,
ALR-n is always set to '1' and an alarm is indicated.
Threshold-Hi-n Registers (n = 0, 1, 2, 3) (Read/Write)
Bit 15
MSB
0
Bit 14
0
Bit 13
0
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
0
THRH11 THRH10 THRH9 THRH8 THRH7
Bit 6
THRH6
Bit 5
THRH5
Bit 4
THRH4
Bit 3
THRH3
Bit 2
THRH2
Bit 1
THRH1
Bit 0
LSB
THRH0
Bits [15:12]
(READ-ONLY)
THRH11–THRH0
'0' when read back. Writing these bits causes no change.
Data bits of the upper bound threshold of the nth analog input. All bits are set to '1'
after power-on or reset.
Threshold-Low-n Registers (n = 0, 1, 2, 3) (Read/Write)
Bit 15
MSB
0
Bit 14
0
Bit 13
0
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Bit 7
0
THRL11 THRL10 THRL9 THRL8 THRL7
Bit 6
THRL6
Bit 5
THRL5
Bit 4
THRL4
Bit 3
THRL3
Bit 2
THRL2
Bit 1
THRL1
Bit 0
LSB
THRL0
Bits [15:12]
(READ-ONLY)
THRL11–THRL0
Always '0' when read back. Writing these bits causes no change.
Data bits of the lower bound threshold of the nth analog input. This register is
cleared to '0' after power-on or reset.
RESET Register (Read/Write)
The AMC7823 has a special RESET Register that performs the software equivalent function of the device
RESET pin. To invoke a system reset, write the data word 0xBB3X to this register. Only the upper 12 bits are
significant; the lowest four bits are Don’t Care.
Bit 15
MSB
1
Bit 14
0
Bit 13
1
Bit 12
1
Bit 11
1
Bit 10
0
Bit 9
1
Bit 8
1
Bit 7
0
Bit 6
0
Bit 5
1
Bit 4
1
Bit 3
X
Bit 2
X
Bit 1
X
Bit 0
LSB
X
X : Don't Care
Any other value written to this register has no effect. After power-on or reset, this register is cleared to all zeros.
Therefore, the value 0x0000 is always read back from this register.
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