Sharp Electronics Corporation Introduces New Voltage Regulator That Simplifies Switching Power Supply Design; Chip Combines Primary-Side Power MOS-FETs and Switching Control IC in a Single T0-220 Package

Business Wire, Jan 4, 1995

CAMAS, Wash.--(BUSINESS WIRE)--Jan. 4, 1995--Sharp Electronics Corporation today announced the PQ1PF1 primary-side voltage regulator -- a device that makes power supplies for computers and office equipment more compact and easier to design. In addition to reducing the size of a switching power supply, the PQ1PF1 also reduces power consumption.

The new voltage regulator is ideal for more compact equipment. Compared to using discrete components, this device reduces the parts count in the switching control circuitry from 12 to just 5 and reduces the mounting area from 5.3 cm square to 2.0 cm square. By integrating a power MOS-FET and its switching control into a single device, Sharp allows equipment manufacturers to more easily develop switching power supplies without having to design complex switching logic P thus shortening design times. The PQ1PF1 reduces power loss from the control logic 1.06 watts to 760 milliwatts.

The PQ1PF1 integrates two new devices -- a power MOS-FET (MOS field effect transistor) with a current sensing pin and a pulse-width modulation control IC with built-in oscillator. Sharp combined these two devices using a multi-chip frame assembly into a compact TO-220 package - the same package that normally houses only the power MOS-FET.

The PQ1PF1 also features built-in protection from thermal and current overload and from low-voltage malfunction. Sharp will soon offer an evaluation board for the PQ1PF1 that lets designers and manufacturers check the operating characteristics of power supplies that use the device for primary-side control. The board helps determine a wide range of characteristics, including power supply efficiency, fluctuations under load, ripple, noise, over-current detection, etc.

Application Areas

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- Power supplies for all types of electronic equipment

such as personal computers, TV sets, VCRs, etc.

- Switching power supplies

Specifications

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Parameter                 Symbol   Rating   Unit   Conditions

Drain-to-source voltage   VDS      500      V      ---
Drain current              ID      4.5      A      ---
Supply voltage (1)        VCC       35      V      ---
FB pin input voltage(2)   VFB        4      V      ---
CA pin input current      ICA        2     mA      ---
Allowable dissipation(3)  Pd1        2      W      ---
                          Pd2       20      W      ---
Junction temperature(4)    Tj      150  deg C      ---
Operating temperature    Topr      -20
                                to  80  deg C      ---
Storage temperature      Tstg      -40
                               to  150  deg C      ---
Soldering temperature    Tsol      260  deg C for 10 seconds

(1)  Voltage between VCC and GND pins.
(2)  Voltage between FB and GND pins.
(3)  Pd1 is the value when self-cooled (free air);
     Pd2 is the value when mounted on an infinitely
     radiating heat sink
(4)  Thermal overload shut-off is activated when Tj is in the
     range from 125 deg C to 150 deg C.