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TEA1211HN датащи(PDF) 7 Page - NXP Semiconductors |
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TEA1211HN датащи(HTML) 7 Page - NXP Semiconductors |
7 / 23 page 2003 Oct 13 7 Philips Semiconductors Preliminary specification High efficiency auto-up/down DC/DC converter TEA1211HN handbook, full pagewidth MDB005 maximum positive spread of VFB maximum negative spread of VFB typical situation lower specification limit upper specification limit +4% −4% 2% VOUT (typ.) Vh Vl 2% Vh Vl Vh Vl 2% Fig.5 Spread of location of output voltage window. Vh = High window limit Vl = Low window limit 7.2.3 SWITCHING SEQUENCE Refer to Figures 1 and 3. In up-mode the cycle starts by making P-down and N-up conducting in the first phase. The second phase N-up opens and P-up starts conducting. In down-mode the cycle starts with in the first phase P-up and P-down conducting. The second phase P-down opens and N-down starts conducting. In PFM these two phases are followed by a third or wait phase that opens all switches except for N-down, which is closed to prevent the coil from floating. The stationary mode or 4-phase cycle, which only occurs in PFM, starts with in the first phase P-down and N-up conducting. In the second phase P-down and P-up conduct forming a short-cut from battery to output capacitor. In the third phase P-up and N-down conduct. The fourth or wait-phase again opens all switches except for N-down which is closed to prevent the coil from floating. 7.3 Adjustable output voltage The output voltage of the TEA1211HN can be set to a fixed value by means of an external resistive divider. After start-up through this divider, dynamic control of the output voltage is made possible by use of an I2C-bus. The output voltage can be programmed from 1.5 V to 5.5 V in 40 steps of 0.1 V each. In case of Power Amplifiers (PAs) for example the output voltage of the TEA1211HN can be adjusted to the output power to be transmitted by the PA, in order to obtain maximum system efficiency. 7.4 Start-up If the input voltage exceeds the start voltage, the TEA1211HN starts ramping up the voltage at the output capacitor. Ramping stops when the target level, set by the external resistors, is reached. 7.5 Under voltage lockout As a result of too high load or disconnection of the input power source, the input voltage can drop too low to guarantee normal regulation. In that case, the device switches to a shut-down mode stopping the switching completely. Start-up is possible by crossing the start-up level again. 7.6 Shut-down When pin SHDWN is made HIGH, the converter disables all switches except for N-down (see Fig.1) and power consumption is reduced to a few µA. N-down is kept conducting to prevent the coil from floating. 7.7 Power switches The power switches in the IC are two N-type and two P-type MOSFETs, having a typical pin-to-pin resistance of 85 m Ω. The maximum continuous input/output current in the switches is 1.7 A at 70 °C ambient temperature. |
Аналогичный номер детали - TEA1211HN |
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Аналогичное описание - TEA1211HN |
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