DP8473 Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – DP8473 Floppy Disk Controller PLUS-2

July 1990
DP8473 Floppy Disk Controller PLUS-2^TM
General Description
This controller is a full featured floppy disk controller that is
software compatible with the mPD765A but also includes
many additional hardware and software enhancements
These enhancements include additional logic specifically re-
quired for an IBM PC PC-XT PC-AT or PS 2 design
This controller incorporates a precision analog data separa-
tor that includes a self trimming delay line and VCO Up to
three external filters are switched automatically depending
on the data rate selected This provides optimal perform-
ance at the standard PC data rates of 250 300 kb s and
500 kb s It also enables optimum performance at 1 Mb s
(MFM) These features combine to provide the lowest possi-
ble PLL bandwidth with the greatest lock range and hence
the widest window margin
This controller includes write precompensation circuitry A
shift register is used to provide a fixed 125 ns early-late
precompensation for all tracks at 500k 300k 250 kb s (83
ns for 1 MB s) or a precompensation value that scales with
(Continued)
Features
Y _{Fully mPD765A and IBM-BIOS compatible}
Y _{Integrates all PCXT PCAT and most PS 2 Logic}
On chip 24 MHz Crystal Oscillator
DMA enable logic
IBM compatible address decode of A0 – A2
12 mA mP bus interface buffers
48 mA floppy drive interface buffers
Data rate and drive control registers
Y _{Precision analog data separator}
Self-calibrating PLL and delay line
Automatically chooses one of three filters
Intelligent read algorithm
Y _{Two pin programmable precompensation modes}
Y _{Other enhancements}
up to 1 Mb s data rate
Implied seek up to 4000 tracks
IBM or ISO formatting
Y _{Low power CMOS with power down mode}
Connection Diagrams
Plastic Leaded Chip Carrier
Dual-In-Line Package
Top View
Order Number DP8473V
See NS Package Number V52A
TL F 9384 – 1
TRI-STATE is a registered trademark of National Semiconductor Corporation
PLUS-2TM is a trademark of National Semiconductor Corporation
IBM PCXT PCAT and PS 2 are registered trademarks of International Business Machines Corporation
C1995 National Semiconductor Corporation TL F 9384
Top View
TL F 9384 – 2
Order Number DP8473N
See NS Package Number N48A
RRD-B30M105 Printed in U S A