TB6674PG, TB6674FG, and TB6674FAG are stepping motor driver ICs with MOS output transistors.
  The ICs can control two-phase stepping motor forward and reverse by bipolar driving. They have a power-saving circuit and a standby circuit. 

FEATUREs
They are similar substituting products of TA7774PG, TA7774FG, and TA7774FAG. Both products have same packages and same pin assignments.
One-chip two-phase bipolar stepping motor driver (including two bridge drivers)
Power saving operation is available.
Standby operation is available. Current consumption ≤20 μA (typ.)
Built-in punch-through current restriction circuit for system ability and noise suppression.
TTL-compatible inputs INA, INB, PS, and Vs2B terminals
ON resistance PS = L : 2.9 Ω(Typ.) 
                   PS = H: 7.9 Ω(Typ.)
High driving ability. 
       
        : IO (START)350 mA (MAX.)  : V_S1 ENABLE
        : IO (HOLD)100 mA (MAX.)  : V_S2 ENABLE
       
        : IO (START)100 mA (MAX.)  : V_S1 ENABLE
        : IO (HOLD)50 mA (MAX.)  : V_S2 ENABLE
Typical PKG  DIP16 pin, HSOP16 pin, SSOP16 pin
GND terminal = HEAT SINK
Process :BiCD0.6 (30 V)
Over current shutdown circuit (ISD).
Thermal shutdown circuit (TSD).
Undervoltage lockout circuit (UVLO).
Pull-down resistance for input terminal (250 kΩ).