TLS24302, TLS24306
2- AND 6-CHANNEL MAGNETORESISTIVE/THIN-FILM
READ/WRITE PREAMPLIFIERS

SQHS007A – DECEMBER 8, 1995 – REVISED DECEMBER 15, 1995

• Current-Bias/Current-Sense Architecture
• Fabricated Using LinIMPAC^TM- CE BiCMOS Technology
• Operates From a Single 5-V Supply (±10%)
• Low-Power Idle Mode
• Single-Ended Input to Reader With One Side Grounded
• True Differential Read Output
• Wide Magnetoresistive (MR) Resistor [R (MR) ] Range From 10 to 40
• MR-Head Bias Current [I I(BIAS) ] Programmable From 7 mA to 17 mA
• Buffered-Head-Voltage [V (_BH) ] Monitor
• Gain: 230 V/V at R (_MR) = 20
• Bandwidth: – 65 MHz at –1 dB [R (_MR) = 20 ] – 140 MHz at –3 dB [R (_MR) = 20 ]
• Equivalent Input Noise = 0.55 nV/ at R (_MR) = 20
• Write-Head Current Programmable From 10 mA to 35 mA (Base to Peak)
• Write-Current Rise/Fall Time = 3.7 ns – L I(TF) (Head Only) = 180 nH – R I(TF) = 15, L (lead) = 50 nH – I I(W) = 25 mA
• Fast Recovery Times: – Write to Read = 0.8 ms (BHV/ =L) – Read to Write = 50 ns
• Output Capacitance = 8.5 pF for Write
• Multichannel Servo Write: – Upper or Lower Half Channels – Every Two Channels – All Channels
• Read-Fault (RUS), Write-Fault (WUS), and Idle-Fault (IUS) Detection
• MR-Head Open Protection and MR-Head Short Detection Available (Metal Option, Disabled)
• Thermal-Asperity Detection Available (Metal Option, Disabled)
• Pseudo-ECL (PECL) Differential-Write-Data (WDX and WDY) Inputs
• Write Data Divided-by-2 (FF) Circuit Available (Metal Option, Disabled)
• Channel Separation 70 dBa at f = 25 MHz
• Power-Supply Rejection Ratio (PSRR) 50 dB at 25 MHz (Input Referred)
• MR Bias On During Write Mode; Otherwise, Programmable On/Off
• Input Control Lines: – Head Select HS (2 Channel) or HS0 – HS2 (6 Channel) With Internal Pullup Resistors – R/W With Internal Pullup Resistor – With Internal Pullup Resistor – BHV/ With Internal Pulldown Resistor
• Packaged in 30-Pin (2 Channel) and 38-Pin (6 Channel) Plastic TSSOP Packages
• Optimized for Package-On-Arm Applications

description

The TLS24302 and TLS24306 are read/write BiCMOS preamplifiers designed for use with magnetoresistive (MR)/thin-film (TF) recording heads. The MR element is used for reading and the inductive thin-film section of the head is used for writing. The preamplifiers implement a current-bias/current-sense architecture. Both have a single-ended read input with a fully differential read (RDX, RDY) output that operates from a single 5-V supply.

The write-head current I I(W) and MR-head bias current I I(BIAS) are programmable using external resistors. Recovery time is reduced by holding BHV/ low during the write mode. Multichannel servo write is achieved by taking FLT/SE higher than V CC by at least 1.2 V. An optional booster circuit can be used to achieve higher operating frequencies.

A fault terminal (FLT/SE) goes low when the WDX/WDY input frequency is low, a head is shorted or open, there is no write current (Ix or Iy), or if V CC is low. Additionally, the preamplifiers provide an optional thermal-asperity detection circuit that can be enabled by using an optional metal mask during the fabrication process.

Table 1 lists the functions that can be changed by a custom metal mask during the fabrication process. Contact your local Texas Instruments (TI) sales office or representative for further information.