1997-04-01 , S/IC-593/650

Philips Semiconductors today announced two new members of its disk drive head pre-amplifier family, the TDA5357 and the TDA5157. The pre-amps are specifically designed for high-end single- and dual-stripe magneto-resistive read/inductive write heads for the disk drive industry. By incorporating thermal asperity detection and recovery, the Philips pre-amps detect and correct for potentially damaging particles on the disk. In addition, the pre-amps feature a serial interface, ensuring easier adaptability and monitoring by reducing the number of pins and lines, and increasing the device's FLEXibility. Only one external component is necessary for pre-amp operation, hence reducing the cost of having the pre-amp on the arm where space is limited.

According to Pierre-Yves Couteau, international product marketing manager for Mass Storage ICs, "As the internal transfer rate of 3.5" high performance disk drives increases to 200 Mb/s and above, at rotational speeds of 7,200 RPM and even 10,000 RPM, noise and thermal issues are critical. The TDA5357 and TDA5157 offer the best high-end performance available. This new offering of single stripe and dual stripe devices closely follows the introduction of our dual-stripe MR pre-amps last September. Philips now offers a complete magneto-resistive solution to the disk drive market."

The TDA5357 is designed for four terminal, single-stripe MR/inductive-write heads. To avoid voltage breakthrough between the heads and disk, the common mode voltage of the MR heads is biased to ground. Dummy head selection protects the MR head during switching. The excellent noise rejection (65 dB for both common mode ejection ratio and power supply rejection ratio) surpasses competitive devices, and yields a superior overall signal-to-noise ratio.

The IC incorporates read amplifiers, write amplifiers, serial interface, digital-to-analog converters, reference and control circuits which operate on a dual supply voltages of +5.0 V and -4.7 V. The complementary output stages of the write amplifier allow writing with near rail-to-rail peak voltages across the inductive write head. The read amplifier has high input impedance (voltage sense architecture), therefore the gain is independent of the head to head MR resistance variation and the head to pre-amp lead inductance does not limit the bandwidth as is the case with current sense architecture. The DC offset between the two terminals of the MR head is eliminated using on-chip AC coupling. Fast settling features - involving the external dummy and fast pin signals - are used to keep the transients short. As an option, the read amplifier may be left biased during writing to further reduce the duration of these transients.

Other programmability features include:

• Programmable voltage/current mode with data input
• Programmable high frequency zero/pole gain-boost and gain attenuator
• Programmable write driver compensation capacitance
• Programmable MR bias currents and write currents

The devices are priced at $6.00 in volume quantities. Fully functional samples are currently available and production quantities (bare die) will be delivered in 4th quarter, 1997. For pricing outside the United States or pre-amp versions with different number of channels, please contact your local Philips Semiconductors sales office or authorised Philips distributor.

Philips Semiconductors, a division of Philips Electronics NV, headquartered in Eindhoven, The Netherlands, is the ninth largest semiconductor supplier in the world and the third largest supplier of discretes in the world. Philips Semiconductors' innovations in digital audio, video, and mobile technology position the company as a leader in the consumer, multimedia and wireless communications markets. Sales offices are located in all major markets around the world and are supported by systems labs.