To provide a power tool capable of lessening the number of components and accurately detecting a discharge voltage limit value and having a remained power quantity warning circuit of a battery pack.
The remained power quantity warning circuit 6 comprises a cathode terminal K connected with a positive electrode side power source supply track NP via a current limiting resistance 63, an anode terminal A connected with a negative electrode side power source supply track LN, and a shunt regulator 64 having a reference terminal RE for applying detection voltage Vd partially divided by a pair of partial voltage detecting resistances 60, 61 connected in series between a pair of power source supply tracks NP and LN. The remained power quantity warning circuit 6 supplies output voltage Vk of the cathode terminal K of the shunt regulator 64 to a control input terminal of an output switching element 72 via a level shift element (voltage conversion element) 65. When a trigger switch 4a is turned on, changes of the output voltage Vk of the cathode terminal K obtained in the shunt regulator 64 are detected by the output switching element 72 via the level shift element 65.
COPYRIGHT: (C)2009,JPO&INPIT
Nobuhiro Takano
Eiji Nakayama
Takashi Ueda
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| JP2004129439A | ||||
| JP2004064977A |