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TEA1533AT データシート(PDF) 6 Page - NXP Semiconductors |
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TEA1533AT データシート(HTML) 6 Page - NXP Semiconductors |
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6 / 24 page  2002 Aug 23 6 Philips Semiconductors Product specification GreenChipTMII SMPS control IC TEA1533T; TEA1533AT Once the drain voltage exceeds the M-level (mains-dependent operation-enabling level), the start-up current source will continue charging capacitor CVCC (switch S1 will be opened); see Fig.2. The IC will activate the converter as soon as the voltage on pin VCC passes the VCC(start) level. The IC supply is taken over by the auxiliary winding as soon as the output voltage reaches its intended level and the IC supply from the mains voltage is subsequently stopped for high efficiency operation (green function). The moment the voltage on pin VCC drops below the undervoltage lock-out level, the IC stops switching and enters a safe restart from the rectified mains voltage. Inhibiting the auxiliary supply by external means causes the converter to operate in a stable, well defined burst mode. Supply management All (internal) reference voltages are derived from a temperature compensated, on-chip band gap circuit. Current mode control Current mode control is used for its good line regulation behaviour. The ‘on-time’ is controlled by the internally inverted control voltage, which is compared with the primary current information. The primary current is sensed across an external resistor. The driver output is latched in the logic, preventing multiple switch-on. The internal control voltage is inversely proportional to the external control pin voltage, with an offset of 1.5 V. This means that a voltage range from 1 to 1.5 V on pin CTRL will result in an internal control voltage range from 0.5 to 0 V (a high external control voltage results in a low duty cycle). Oscillator The maximum fixed frequency of the oscillator is set by an internal current source and capacitor. The maximum frequency is reduced once the control voltage enters the VCO control window. Then, the maximum frequency changes linearly with the control voltage until the minimum frequency is reached (see Figs 5 and 6). Cycle skipping At very low power levels, a cycle skipping mode will be activated. A high control voltage will reduce the switching frequency to a minimum of 25 kHz. If the voltage on the control pin is raised even more, switch-on of the external power MOSFET will be inhibited until the voltage on the control pin has dropped to a lower value again (see Fig.7). For system accuracy it is not the absolute voltage on the control pin that will trigger the cycle skipping mode, but a signal derived from the internal VCO will be used. Remark 1: If the no-load requirement of the system is such that the output voltage can be regulated to its intended level at a switching frequency of 25 kHz or above, the cycle skipping mode will not be activated. Remark 2: As switching will stop when the voltage on the control pin is raised above a certain level, the burst mode has to be activated by a microcontroller or any other circuit sending a 30 µs, 16 mA pulse to the control input (pin CTRL) of the IC. handbook, halfpage VCTRL 1 V (typ) 0.52 V 1.5 V (typ) MGU233 Vsense(max) Fig.5 Vsense(max) voltage as function of VCTRL. handbook, halfpage Vsense(max) (V) MGU509 f (kHz) 25 175 175 kHz VCO2 level VCO1 level Fig.6 VCO frequency as function of Vsense(max) |
同様の部品番号 - TEA1533AT |
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同様の説明 - TEA1533AT |
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