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.
Product Name NJM2857
Function 1.5A output-current LDO
Applications AV devices such as TV and DVD Motor driving in OA equipments such as printer and projector
Packaging TO-252-5(6.54×9.68×2.29mm typ.)

[Features & Characteristics]


A detailed spec is here