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TEA1530T 数据表(PDF) 8 Page - NXP Semiconductors |
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TEA1530T 数据表(HTML) 8 Page - NXP Semiconductors |
8 / 21 page TEA1530T_AT_AP_1 © NXP B.V. 2008. All rights reserved. Product data sheet Rev. 01 — 30 June 2008 8 of 21 NXP Semiconductors TEA1530T/AT/AP GreenChip II SMPS control IC 7.10 Minimum and maximum on-time The minimum on-time of the SMPS is determined by the LEB time (typically 400 ns). The IC limits the maximum on-time by limiting the driver duty cycle to 70 %. So the maximum on-time is correlated to the oscillator time which results in an accurate limit of the minimum input voltage of the flyback converter. 7.11 PROTECT and timing input The PROTECT input (pin 3) is a multipurpose, high-impedance input, which can be used to switch off the IC and create a relatively long timing function. As soon as the voltage on this pin rises above 2.5 V, switching stops immediately. For the timing function, a current of typically 50 µA flows out of pin PROTECT and charges an external capacitor until the activation level of 2.5 V is reached. This current source is only activated when the converter is not in regulation, which is detected by the voltage on pin CTRL (VCTRL < 0.63 V). A (small) discharge current is also implemented to ensure that the capacitor is not charged, for example, by spikes. An internal MOSFET switch is added to discharge the external capacitor and ensures a defined start situation. For the TEA1530AP and TEA1530AT the voltage on pin CTRL determines whether the IC enters latched protection mode or safe restart protection mode: • When the voltage on pin CTRL is below 0.63 V, the IC is assumed to be out of regulation (e.g. the control loop is open). In this case activating pin PROTECT (VPROTECT > 2.5 V) will cause the converter to stop switching. Once VCC drops below Vth(UVLO), capacitor CVCC will be recharged and the supply will restart. This cycle will be repeated until the fault condition is removed (safe restart mode). • When the voltage on pin CTRL is above 0.63 V, the output is assumed to be in regulation. In this case activating pin PROTECT (VPROTECT > 2.5 V), by external means, will activate the latch protection of the IC. The voltage on pin VCC will cycle between Vstartup and Vth(UVLO), but the IC will not start switching again until the latch Fig 6. Slope compensation 014aaa255 CTRL −1 0.63 V control detect 5.6 V 4 RCTRL Rslopecomp ∆Isc/∆t |
类似零件编号 - TEA1530T |
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类似说明 - TEA1530T |
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