DP8464B Datasheet | National Semiconductor

Description The DP8464B Disk Pulse Detector utilizes analog and digital circuitry to detect amplitude peaks of the signal received from the read write amplifier fitted with the heads of disk drives The DP8464B produces a TTL patible output which on the positive leading edge indicates a signal peak Electrically these peaks correspond to flux reversals on the magnetic medium The signal from the read write amplifier when reading a disk is therefore a series of pulses with alternating polarity The Disk Pulse Detector accurately replicates the time position of these peaks The DP8464B Disk Pulse Detector has three main sections the Amplifier the time channel and the gate channel The Amplifier section consists of a wide bandwidth amplifier a full wave rectifier and Automatic Gain Control (AGC) The time channel is made from the differentiator and its following bi-directional one shot while the gate channel is made from the differential parator with hysteresis the D flipflop and its following bi-directional one shot The Disk Pulse Detector is fabricated using an advanced oxide isolated Schottky process and has been designed to function with data rates up to 15 Megabits second The DP8464B is available in either a 300 mil wide 24-pin dual-inline package or a surface mount 28-pin plastic chip carrier package Normally it will be fitted in the disk drive and its output may be directly connected to the DP8461 or the DP8465 Data Separator Features Wide input signal amplitude range from 20 m Vpp to 660 m Vpp differential Data rates up to 15 Megabits sec 2 7 code On-chip differential gain controlled amplifier differentiator parator gating circuitry and output pulse generator Input capacitively coupled directly from the disk head read write amplifier Adjustable parator hysteresis AGC and differentiator time constants set by external ponents TTL patible digital Inputs and Outputs Encoded Data Output may connect directly to the DP8461 or DP8465 Data Separator...