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TEA1506T 数据表(PDF) 6 Page - NXP Semiconductors |
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TEA1506T 数据表(HTML) 6 Page - NXP Semiconductors |
6 / 22 page 2003 Sep 09 6 Philips Semiconductors Product specification GreenChip ™II SMPS control IC TEA1506P; TEA1506AP; TEA1506T; TEA1506AT FUNCTIONAL DESCRIPTION The TEA1506 is the controller of a compact flyback converter, and is situated at the primary side. An auxiliary winding of the transformer provides demagnetization detection and powers the IC after start-up. The TEA1506 can operate in multi modes (see Fig.5). The next converter stroke is started only after demagnetization of the transformer current (zero current switching), while the drain voltage has reached the lowest voltage to prevent switching losses (green function). The primary resonant circuit of the primary inductance and drain capacitor ensures this quasi-resonant operation. The design can be optimized in such a way that zero voltage switching can be reached over almost the universal mains range. To prevent very high frequency operation at lower loads, the quasi-resonant operation changes smoothly in fixed frequency PWM control. At very low power (standby) levels, the frequency is controlled down, via the VCO, to a minimum frequency of approximately 25 kHz. Start-up and undervoltage lock-out Initially the IC is in the save restart mode. As long as VCC is below the VCC(start) level, the supply current is nearly zero. 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. The moment the voltage on pin VCC drops below the undervoltage lock-out level, the IC stops switching and re-enters the safe restart 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 6 and 7). handbook, halfpage VCO fixed quasi resonant P (W) MGU508 f (kHz) 25 175 Fig.5 Multi modes operation. handbook, halfpage VCTRL 1 V (typ) 0.52 V 1.5 V (typ) MGU233 Vsense(max) Fig.6 Vsense(max) voltage as function of VCTRL. |
类似零件编号 - TEA1506T |
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类似说明 - TEA1506T |
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