FDC37C78-HT datasheet(59/82 Pages) MICROCHIP

59 / 82 page

Once awake, the FDC37C78 will

reinitiate

the

auto powerdown timer for 10 ms. The part will

powerdown

again

when

all

the

powerdown

conditions are satisfied.

Table 30 reiterates the AT registers available. It

also shows the type of access permitted. In order

to maintain software transparency, access to all

the registers must be maintained.

As Table 30

shows, two sets of registers are distinguished

based on whether their access results in the part

remaining in powerdown state or exiting it.

Access to all other registers is possible without

awakening the part.

These registers can be

accessed during powerdown without changing the

status of the part. A read from these registers will

reflect the true status as shown in the register

description in the FDC description. A write to the

part will result in the part retaining the data and

subsequently reflecting it when the part awakens.

Accessing the part during powerdown may cause

an increase in the power consumption by the

part. The part will revert back to its low power

mode when the access has been completed.

Pin Behavior

The FDC37C78 is

specifically

designed

for

portable PC systems in which power conservation

is a primary concern. This makes the behavior of

the pins during powerdown very important.

The pins of the FDC37C78 can be divided into

two major categories: system interface and floppy

disk drive interface. The floppy disk drive pins are

disabled so that no power will be drawn through

the part as a result of any voltage applied to the

pin within the part's power supply range. Most of

the system interface pins are left active to monitor

system accesses that may wake up the part.

System Interface Pins

Table 31 gives the state of the system interface

pins in the powerdown state.

Pins unaffected by

the powerdown are labeled "Unchanged". Input

pins are "Disabled" to prevent them from causing

currents internal to the FDC37C78 when they have

indeterminate input values.

FDC37C78-HT Datasheet(PDF) 59 Page - Microchip Technology

FDC37C78-HT Datasheet(HTML) 59 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82

Datasheet Download

Link URL