ADM1168 Analog Devices, ADM1168 Datasheet - Page 11

• Manufacturer Part Number: ADM1168
• Description: Super Sequencer and Monitor with Nonvolatile Fault Recording
• Manufacturer: Analog Devices

Specifications of ADM1168

• # Supplies Monitored: 8
• Volt Monitoring Accuracy: 1%
• # Output Drivers: 8
• Fet Drive/enable Output: Both
• Package: 32 ld LQFP

INPUTS
SUPPLY SUPERVISION
The ADM1168 has eight programmable inputs. Four of these
are dedicated supply fault detectors (SFDs). These dedicated
inputs are called VH and VPx (VP1 to VP3) by default. The
other four inputs are labeled VXx (VX1 to VX4) and have dual
functionality. They can be used either as SFDs, with functionality
similar to the VH and VPx, or as CMOS-/TTL-compatible logic
inputs to the device. Therefore, the ADM1168 can have up to
eight analog inputs, a minimum of four analog inputs and four
digital inputs, or a combination thereof. If an input is used as
an analog input, it cannot be used as a digital input. Therefore, a
configuration requiring eight analog inputs has no available
digital inputs. Table 6 shows the details of each input.
PROGRAMMING THE SUPPLY FAULT DETECTORS
The ADM1168 can have up to eight SFDs on its eight input
channels. These highly programmable reset generators enable
the supervision of up to eight supply voltages. The supplies can
be as low as 0.573 V and as high as 14.4 V. The inputs can be
configured to detect an undervoltage fault (the input voltage
drops below a preprogrammed value), an overvoltage fault (the
input voltage rises above a preprogrammed value), or an out-of-
window fault (the input voltage is outside a preprogrammed
range). The thresholds can be programmed to an 8-bit resolution
in registers provided in the ADM1168. This translates to a
voltage resolution that is dependent on the range selected.
The resolution is given by
Therefore, if the high range is selected on VH, the step size can
be calculated as follows:
Step Size = Threshold Range/255
(14.4 V − 6.0 V)/255 = 32.9 mV
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Table 5 lists the upper and lower limits of each available range,
the bottom of each range (V
Table 5. Voltage Range Limits
Voltage Range (V)
0.573 to 1.375
1.25 to 3.00
2.5 to 6.0
6.0 to 14.4
The threshold value required is given by
where:
V
V
N is the decimal value of the 8-bit code.
V
Reversing the equation, the code for a desired threshold is given by
For example, if the user wants to set a 5 V overvoltage threshold
on VP1, the code to be programmed in the PS1OVTH register
(as described in the
Therefore, N = 182 (1011 0110 or 0xB6).
T
R
B
is the desired threshold voltage (undervoltage or overvoltage).
is the voltage range.
is the bottom of the range.
V
N = 255 × (V
N = 255 × (5 − 2.5)/3.5
T
= (V
R
× N)/255 + V
T
AN-721 Application
− V
B
)/V
B
R
B
), and the range itself (V
V
0.573
1.25
2.5
6.0
B
(V)
Note) is given by
ADM1168
V
0.802
1.75
3.5
8.4
R
R
(V)
).