ADM1062ASU datasheet(13/32 Pages) AD

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Preliminary Technical Data

ADM1062

Rev. PrJ | Page 13 of 32

ADM1062 INPUTS

POWERING THE ADM1062

The ADM1062 is powered from the highest voltage input on

either the Positive Only supply inputs (VPn) or the High

Voltage supply input (VH). The same pins are used for supply

fault detection (discussed below) . A VDD Arbitrator on the

device chooses which supply to use. The arbitrator can be

considered an OR’ing of five LDO’s together. A supply

comparator chooses which of the inputs is highest and selects

this one to provide the on- chip supply. There is minimal

switching loss with this architecture (~0.2V), resulting in the

ability to power the ADM1062 from a supply as low as 3.0V.

Note that the supply on the VXn pins cannot be used to power

the device.

An external cap to GND is required to decouple the on chip

supply from noise. This cap should be connected to the

VDDCAP pin, as shown in Figure 22. The cap has another use

during “brown outs” (momentary loss of power). Under these

conditions, where the input supply, VPn or VH, dips transiently

below VDD, the synchronous rectifier switch immediately turns

off so that it doesn’t pull VDD down. The VDD cap can then act

like a reservoir and keep the device active until the next highest

supply takes over the powering of the device. 10µF is

recommended for this reservoir/decoupling function.

Note that in the case where there are two or more supplies

within 100mV of each other, the supply which takes control of

VDD first will keep control (e.g) if VP1 is connected to a 3.3V

supply, then VDD will power up to approximately 3.1V through

VP1. If VP2 is then connected to another 3.3V supply, VP1 will

still power the device, unless VP2 goes 100mV higher than VP1.

Figure 22. VDD Arbitrator Operation

The ADM1062 has ten programmable inputs. Five of these are

dedicated Supply Fault Detectors (SFD’s). These dedicated

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

have dual functionality. They can either be used as Supply Fault

Detectors, with similar functionality to VH and VP1-4, or they

can be used as CMOS/TTL compatible logic inputs to the

devices. Thus, the ADM1062 can have up to ten analog inputs, a

minimum of five analog inputs and five digital inputs, or a mix.

Note that if an input is used as an analog input, it cannot be

used as a digital input. Thus, a configuration requiring ten

analog inputs would have no digital inputs available. Table 4

shows the details of each of the inputs.

Table 4. Input Functions, Thresholds and Ranges

Input

Function

Voltage Range

Max Hysteresis

Voltage Resolution

Glitch Filter

High V Analog Input

2.5V to 6V

425mV

13.7mV

0-100µs

4.8V to 14.4V

1.16V

37.6mV

0-100µs

VPn

Positive Analog Input

0.573 to 1.375V

97.5mV

3.14mV

0-100µs

1.25 to 3V

212mV

6.8mV

0-100µs

2.5 to 6V

425mV

13.7mV

0-100µs

VXn

High Z Analog Input

0.573 to 1.375V

97.5mV

3.14mV

0-100µs

Digital Input

0 to 5V

N/A

0-100µs

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