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ADM1068ACP-REEL

Super Sequencer™ and Monitor

Analog Devices 

Preliminary Technical Data

ADM1068

INPUTS

SUPPLY SUPERVISION

The ADM1068 has eight programmable inputs. Four of these

are dedicated supply fault detectors (SFDs). These dedicated

inputs are called VH and VP1–3 by default. The other four

inputs are labeled VX1–VX4 and have dual functionality. They

can be used as either supply fault detectors, with similar

functionality to VH and VP1–3, or CMOS/TTL-compatible

logic inputs to the devices. Therefore, the ADM1068 can have

up to eight analog inputs, a minimum of four analog inputs and

four digital inputs, or a combination. 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 digital inputs

available. Table 5 shows the details of each of the inputs.

ULTRA

LOW

VPn

RANGE

SELECT

VREF

OV

+ COMPARATOR

–

GLITCH

FILTER

FAULT

OUTPUT

LOW

MID

+

–

UV

FAULT TYPE

COMPARATOR SELECT

Figure 15. Supply Fault Detector Block

PROGRAMMING THE SUPPLY FAULT DETECTORS

The ADM1068 has up to eight supply fault detectors (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 droops below a preprogrammed value), an

overvoltage fault (the input voltage rises above a

preprogrammed value) or an out-of-window fault

(undervoltage or overvoltage). The thresholds can be

programmed to an 8-bit resolution in registers provided in the

ADM1068. This translates to a voltage resolution that is

dependent on the range selected.

The resolution is given by

Step Size = Threshold Range/255

Therefore, if the high range is selected on VH, the step size can

be calculated as follows:

(14.4 V − 4.8 V)/255 = 37.6 mV

Table 4 lists the upper and lower limit of each available range,

the bottom of each range (VB), and the range itself (VR).

Table 4. Voltage Range Limits

Voltage Range (V)

0.573 to 1.375

1.25 to 3.00

2.5 to 6.0

4.8 to 14.4

VB (V)

0.573

1.25

2.5

4.8

VR (V)

0.802

1.75

3.5

9.6

The threshold value required is given by

VT = (VR × N)/255 + VB

where:

VT is the desired threshold voltage (UV or OV).

VR is the voltage range.

N is the decimal value of the 8-bit code.

VB is the bottom of the range.

Reversing the equation, the code for a desired threshold is

given by

N = 255 × (VT − VB)/VR

For example, if the user wants to set a 5 V OV threshold on VP1,

the code to be programmed in the PS1OVTH register

(discussed in the AN-698 application note) is given by

N = 255 × (5 − 2.5)/3.5

Therefore, N = 182 (1011 0110 or 0xB6).

Table 5. Input Functions, Thresholds, and Ranges

Input Function

Voltage Range (V)

VH

High V Analog Input

2.5–6.0

4.8–14.4

VPn Positive Analog Input 0.573–1.375

1.25–3.00

2.5–6.0

VXn High Z Analog Input

0.573–1.375

Digital Input

0–5

Maximum Hysteresis

425 mV

1.16 V

97.5 mV

212 mV

425 mV

97.5 mV

N/A

Voltage Resolution (mV)

13.7

37.6

3.14

6.8

13.7

3.14

N/A

Glitch Filter (µs)

0–100

0–100

0–100

0–100

0–100

0–100

0–100

Rev. PrB | Page 11 of 28

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