公开(公告)号：JPH11149605A

公开(公告)日：1999-06-02

申请号：JP26015498

申请日：1998-09-14

Applicant: ST MICROELECTRON INC

Inventor： AXEL ALLEGRET DE LA SJORLES ,  ALBINO PIDUTTI ,  PAKRISWAMI ELANGO

IPC: G11B5/09

Abstract: PROBLEM TO BE SOLVED: To quickly drive the coil of a write head by connecting transistors passing additional currents parallely with lower side transistors constituting an H dridge driving the coil of the write head and making the leading edge of the pulse of a coil current overshoot temporarily. SOLUTION: Additional transistors 60, 62 receive inverted input signals of signals being on input lines 51, 52 via variable capacitors 64, 66 to be switched simultaneously with lower side transistors 47, 49 to pass additional currents with respect to a coil 50. The additional currents by ways of the transistors 60, 62 do not receive the restriction of the Miller current of a reference current source 70. Then, the current of the coil 50 is made to overshoot temporarily by setting the variable capacitors 64, 66 in proper ratios with respect to variable capacitors 54, 56 and passing the additional currents by ways of the transistor 60, 62 only in parts of desired ratios during desired transition time by the lower side transistors 47, 49.

公开(公告)号：JPH11149604A

公开(公告)日：1999-06-02

申请号：JP26003098

申请日：1998-09-14

Applicant: ST MICROELECTRON INC

Inventor： ALBINO PIDUTTI ,  AXEL ALLEGRET DE LA SJORLES ,  PAKRISWAMI ELANGO

IPC: G11B5/09

Abstract: PROBLEM TO BE SOLVED: To quickly drive the coil of a write head being an inductive load by applying currents into gates of lower side transistors constituting an H bridge circuit driving the coil of the write head, via boost capacitors. SOLUTION: Boost capacitor circuits 40, 41 consisting of respective pairs of transistors 43, 44 and 46, 47 are respectively connected to gates of transistor 13, 15 via boost capacitors 50, 52. Here, capacitances of the boost capacitors are set so as to be respectively same as gate-to-source capacitances of the transistors 13, 15. Then, the transistors 13, 15 are switched in an H bridged coil driving circuit 20, for example, the transistors 13, 15 are made to be in conduction states. In this process, when the upper side of the capacitor 50 is switched from the ground to a Vcc by way of the MOS transistor 43, current is applied into the gate of the transistor 13 via the capacitor 50.