Built-in reversed current protection circuit and small package provide cost reduction and space saving to various equipments
November 24, 2009
New Japan Radio releases the NJM2857, 1.5A output-current LDO
November 24, 2009 - New Japan Radio Co., Ltd has introduced to the market, the NJM2857, 1.5A output-current LDO, suitable for the power unit of TV, DVD, printer and projector.
[Background of development]
Recently, AV (Audio Visual) devices such as TV, DVD and OA (Office Automation) equipments are required high current power supply, because of adding multiple functions to them. So they demand high output current LDO as a POL (Point-of-Load). Therefore, the LDO is required high output current and also miniaturization. To meet theses needs, New Japan Radio Co., Ltd. has developed the NJM2857.
The NJM2857 consists of constant-voltage circuit, ON/OFF control circuit, reversed current protection circuit, over-current protection circuit and thermal overload protection circuit.
- 1.Built-in reversed current protection circuit
- For stable operation, LDO is usually required capacitor connecting at output terminal. There is, however, a risk to destroy it from reverse current by discharge offset voltage. Therefore, it is necessary to add a SBD (Schottky barrier diode) as a protection circuit. The NJM2857 has a built-in protection circuit, and it becomes the SBD unnecessary.
- 2.High maximum input voltage and wide output voltage range
- AV devices and OA equipments are required high current power supply, so they demand high output current LDO as a POL. The NJM2857 has 1.5A, high current output, suitable for AV devices and OA equipments. And it also provides excellent AC characteristics such as high ripple rejection ratio (80 dB typ.) and low noise (Vno=55µVrms typ.).
- 3.Using small size 2.2 µF ceramic capacitor is available
- The NJM2857 has realized using ceramic capacitor as output capacitor, by circuit layout optimization. It provides the cost down and space saving of the mounted board.
||1.5A output-current LDO
||AV devices such as TV and DVD Motor driving in OA equipments such as printer and projector
[Features & Characteristics]
- High ripple rejection ratio 80dB typ. f=1kHz
- Low noise VNO = 55µVrms typ.(Vo=3.0V)
- Using ceramic capacitor available
- Maximum output current 1.5A
- High precision output voltage Vo±1.0%
- ON/OFF control
- Built-in reverse current protection circuit
- Built-in thermal overload protection circuit
- Built-in over-current protection circuit
- Bipolar technology
- Package outline TO-252-5(6.54×9.68×2.29mm typ.)
- Engineering Samples(ES) : already available from October 2009
- Mass Production(MP) : From December 2009