EVALADM1065TQEB Analog Devices Inc, EVALADM1065TQEB Datasheet - Page 10

• Manufacturer Part Number: EVALADM1065TQEB
• Manufacturer: Analog Devices Inc

Specifications of EVALADM1065TQEB

• Lead Free Status / Rohs Status: Not Compliant

ADM1065
POWERING THE ADM1065
The ADM1065 is powered from the highest voltage input on either
the positive-only supply inputs (VPx) or the high voltage supply
input (VH). This technique offers improved redundancy because
the device is not dependent on any particular voltage rail to keep it
operational. The same pins are used for supply fault detection
(see the Supply Supervision section). A V
device chooses which supply to use. The arbitrator can be
considered an OR’ing of five low dropout regulators (LDOs)
together. A supply comparator chooses the highest input to
provide the on-chip supply. There is minimal switching loss with
this architecture (~0.2 V), resulting in the ability to power the
ADM1065 from a supply as low as 3.0 V. Note that the supply on
the VXx pins cannot be used to power the device.
An external capacitor to GND is required to decouple the on-chip
supply from noise. This capacitor should be connected to the
VDDCAP pin, as shown in Figure 15. The capacitor has another
use during brownouts (momentary loss of power). Under these
conditions, when the input supply (VPx or VH) dips transiently
below V
off so that it does not pull V
then act as a reservoir to keep the device active until the next
highest supply takes over the powering of the device. A 10 μF
capacitor is recommended for this reservoir/decoupling function.
The VH input pin can accommodate supplies up to 14.4 V, which
allows the ADM1065 to be powered using a 12 V backplane supply.
In cases where this 12 V supply is hot swapped, it is recommended
that the ADM1065 not be connected directly to the supply. Suitable
precautions, such as the use of a hot swap controller, should be
taken to protect the device from transients that could cause
damage during hot swap events.
DD
, the synchronous rectifier switch immediately turns
DD
down. The V
DD
DD
arbitrator on the
capacitor can
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When two or more supplies are within 100 mV of each other,
the supply that first takes control of V
example, if VP1 is connected to a 3.3 V supply, V
to approximately 3.1 V through VP1. If VP2 is then connected
to another 3.3 V supply, VP1 still powers the device unless VP2
goes 100 mV higher than VP1.
VP1
VP2
VP3
VP4
VH
Figure 15. V
COMPARATOR
SUPPLY
DD
Arbitrator Operation
DD
IN
EN
IN
EN
IN
EN
IN
EN
IN
EN
keeps control. For
4.75V
4.75V
4.75V
4.75V
4.75V
LDO
LDO
LDO
LDO
LDO
OUT
OUT
OUT
OUT
OUT
DD
VDDCAP
powers up
INTERNAL
DEVICE
SUPPLY