July 14, 2008

Driver IC for DC Brush Motors - 4 A Output Current -
STA6940M Released
Adoption of compact package reduces mounting surface area by half

Sanken Electric Co., Ltd. announces the release of the STA6940M, a driver IC for DC brush motors. The device adopts a compact package that reduces the mounting surface area to about half that of conventional ICs, while remaining able to handle a large output current of 4 A (peak: 8 A). Sample shipments are scheduled to begin in early August 2008, with a pre-tax sample price of 800 yen. Mass production shipments are planned to begin in November 2008, starting with a monthly production of 10,000 units, with monthly production expected to ramp up to 50,000 units in fiscal year 2009.
1. Development Background and product overview
  The commonly available driver ICs in commercial use for DC brush motors can handle a peak output current of 1 to 3 A, but motors used in ticket vending machines and ATMs, as well as in optional devices for copiers such as staplers and hole punchers, demand ICs that can handle output currents of about 4 A, which is needed for producing large torque. Nevertheless, few types of ICs can handle an output current approaching 4 A and their multichip structures (with control and power sections separated, and multiple chips being made into one package) tend to make them large size, so miniaturizing their drive circuits has been quite difficult.
Sanken Electric has responded by developing the driver IC STA6940M for DC brush motors. While maintaining the same multichip structure, the STA6940M adopts an 18-pin STA package, which has enjoyed long years on the OA market with proven high thermal dissipation capabilities and reliability, in addition to having been designed to minimize the space required for our SIP packages.  The result is enhanced space saving with a mounting area of about half, and a height above the substrate of about two-thirds, that of conventional ICs, while achieving the ability to handle the higher output current of 4 A.
The STA6940M has a wealth of built-in protection functions, such as self-recovery type undervoltage protection, overcurrent protection, and overheating protection. Furthermore, this IC is equipped with a monitor pin for outputting the operation statuses of these protection functions, thereby contributing to improved device reliability.
It should be noted that the STA6940M is our first IC for large currents, expanding our lineup of driver ICs for DC brush motors to eight types, ranging from 0.65 to 4 A.
2. Features
(1) Compact package adopted: 18-pin STA (resin section dimensions: 25 mm × 9 mm × 4 mm)
(2) Low loss due to adoption of low on-resistance (0.1 Ω typ.) MOSFET
(3) Few control signal lines (forward rotation, reverse rotation, braking, and free operation can be selected using only 2 lines)
(4) Various protection functions:
  • Overcurrent protection (self-recovery type)
  • Overheating protection (self-recovery type)
  • Undervoltage protection (self-recovery type)
    (Protection circuit for stopping operation if the main power supply or logic power supply voltage drops too low.)
  • Monitor pin for outputting protection operation status
  • Dead time function for avoiding shoot-through currents
  • (5) Paralleling two of these ICs allows 2-phase stepping motor bipolar drive exceeding 3 A.
    3. Applications
      Optional devices for copiers (e.g., staplers, hole punchers), ATMs (card readers, coin and bill differentiation), ticket vending machines (coin feeding), gaming devices (slot machines), and more.
    4. Specifications
    Parameter Symbol Rated Value Unit
    Main power supply voltage VBB 10 to 40 V
    Output current Io 4.0 A
    Output current (peak) Io(Peak) 8.0 A
    Output MOSFET on-resistance RDS(ON) 0.1 Ω
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