发明名称 |
Boost controller capable of step-up ratio control |
摘要 |
A charge pump circuit boosts a voltage of a battery so as to generate a drive voltage for an LED. A constant current circuit generates a constant current to feed through the LED. A monitoring circuit monitors a cathode potential of the LED, i.e., a voltage across the constant current circuit. A control circuit receives a result of monitoring from the monitoring circuit 110 and increases a step-up ratio of the charge pump circuit when the voltage across the constant current circuit drops below a minimum voltage that guarantees a constant current. The control circuit sets an externally requested constant current value in the constant current circuit. When a change from a large current to a small current is requested, the control circuit returns the step-up ratio of the charge pump circuit to 1.0.
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申请公布号 |
US2005231127(A1) |
申请公布日期 |
2005.10.20 |
申请号 |
US20050083516 |
申请日期 |
2005.03.18 |
申请人 |
YAMAMOTO ISAO;ARAKI KYOICHIRO;KAGEMOTO NOBORU |
发明人 |
YAMAMOTO ISAO;ARAKI KYOICHIRO;KAGEMOTO NOBORU |
分类号 |
H02J7/00;G05F1/56;H02M3/00;H02M3/07;H05B33/08;H05B37/02;(IPC1-7):H05B37/02 |
主分类号 |
H02J7/00 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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