ADM1066 datasheet(13/32 Pages) AD

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ADM1066

Rev. 0 | Page 13 of 32

INPUTS

SUPPLY SUPERVISION

The ADM1066 has ten programmable inputs. Five of these are

dedicated supply fault detectors (SFDs). These dedicated inputs

are called VH and VP1–4 by default. The other five inputs are

labeled VX1–VX5 and have dual functionality. They can be

used as either supply fault detectors, with similar functionality

to VH and VP1–4, or CMOS/TTL-compatible logic inputs to

the devices. Therefore, the ADM1066 can have up to ten analog

inputs, a minimum of five analog inputs and five 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 ten analog inputs has no digital inputs available.

Table 5 shows the details of each of the inputs.

–

COMPARATOR

VREF

FAULT TYPE

SELECT

COMPARATOR

FAULT

OUTPUT

GLITCH

FILTER

VPn

MID

LOW

RANGE

SELECT

ULTRA

LOW

Figure 22. Supply Fault Detector Block

PROGRAMMING THE SUPPLY FAULT DETECTORS

The ADM1066 has up to ten supply fault detectors (SFDs) on its

ten input channels. These highly programmable reset generators

enable the supervision of up to ten 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 ADM1066. 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)

VB (V)

VR (V)

0.573 to 1.375

0.573

0.802

1.25 to 3.00

1.25

1.75

2.5 to 6.0

2.5

3.5

4.8 to 14.4

4.8

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

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)

Maximum Hysteresis

Voltage Resolution (mV)

Glitch Filter (µs)

High V Analog Input

2.5–6.0

425 mV

13.7

0–100

4.8–14.4

1.16 V

37.6

0–100

VPn

Positive Analog Input

0.573–1.375

97.5 mV

3.14

0–100

1.25–3.00

212 mV

6.8

0–100

2.5–6.0

425 mV

13.7

0–100

VXn

High Z Analog Input

0.573–1.375

97.5 mV

3.14

0–100

Digital Input

0–5

N/A

0–100

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