During 2012, Toshiba has released a really interesting new bipolar stepper motor driver: theTB6600hq(hg). It can be considered, in our opinion, an enhanced version of the 'old' TB6560ahq because, while maintains the same efficiency of the old one, it is characterized by some peculiarities. We can find, infact: 

• single power supply - an internal 5V generator (Vreg) is provided for the logic- max 50V;
• step-dir-enable pins;
• http://cuteminds.com/templates/ja_purity_ii/images/bullet.gif); line-height: 19px; overflow: hidden; text-align: justify; background-position: 20px 7px; background-repeat: no-repeat no-repeat;">1/1 upto 1/16 step;
• 5 Amp. max peak current/phase (3.5 is a more realistic value) remembering that output current is always limited by max power dissipation value;
• thermal, over-current and under voltage controls built in;
• current levels selectable, as usual, providing the right value of Vref accordingly to the NFab resistors;
• monitor and alert pins;
• torque setting pin;
• upto 200Khz clock frequency;
• step pulse of only 2.2 us.

Must be underlined the differences between the two versions (HG and HQ). According to the datasheets such components are very similar but they have a different VRef voltage to set the current of the stepper driver. 0.3 - 1.95V for the HG version 0.3-3.5V for the HQ version (thanks Eric). 

As usual here follows a schematic:

Important:

• NFA-B resistors have a value of 0.25 ohms (better 2512 smd current sensing resistors or multiple parallel resistors) the minimum value. Such a value can be modified according to the Vref voltage. The current/phase, in fact, will be set according to the following formula:  (Vref/3)/R. (we have used 4 1ohm resistors)
• TQ pin sets the torque: H=100% L=33%.
• Monitor and Alert pins can provide only 1ma. A double inverter port connected to such pins can provide the current necessary to drive a led;
• The two filters capacitors must be put as closest as possible to the  tb6600hq power pins (6-20);

• The R4-R5 resistors (regarding the Vref) must be recalculated according to the version of the TB6600 (HQ or HG).
  
  

The poject worked immediately without any surprise. The board has been connected to a small hybrid nema 17 stepper motor (1.5A/phase, 3V, 5.6ohm) and at 1/16 of step we could reach 250khz without any appreciable lost of torque. powering it at 19V only, the motor stalled at 350khz, really interesting.