AN45 SILABS [Silicon Laboratories], AN45 Datasheet
AN45
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AN45 Summary of contents
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... Copyright © 2003 by Silicon Laboratories AN45 Telephone LINE Hook SW. 2 LINE 2 Ringer RDC 7000 R ----------------- - = NREN NREN , the line resistance, and the internal × 7000 RINGrms × -------------------------------------- - ----------------- - ⁄ LINE 7000 NREN NREN , TR_PK s AN45-050 ...
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... AN45 Considering the resistance of 26 gauge telephone wire, which is 0.45 Ω per feet, this equation becomes the following: × 7000 RINGrms × V -------------------------------------- - ----------------- - = + ⁄ TR_PK 7000 NREN NREN Equation 1 The required V is equal to V BAT TR_PK is the voltage drop across the linefeed circuit. The VCMR voltage is set by the indirect Register 40 and recommended ...
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... The output power can be related to inductor power with the efficiency factor, which is defined as the ratio of the output power over the input power. P OUT Rev. 0.5 AN45 C14 0.1 µ R21 VBAT RFILT C26 CFILT ...
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... AN45 In the Discontinuous Switching mode, the current flowing in the inductor always starts the beginning of on-time of Q7, peaks at the end of the on-time, and goes back to zero at the end of off-time. During on-time presented across the L1 inductor DC and the current flow increases linearly (see Figure 3) with respect to the on-time duration of Q7 ...
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... Table 1 lists the requirements for the switching transistor, Q7. Table 1. Switching Transistor Q7 I CMAX are clearly BAT Another critical specification is the transistor gain The higher the transistor gain (h CMAX base current is required to keep it in saturation during Rev. 0.5 AN45 T -------------- - = 61 ns Equation 14 ( × ⁄ ...
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... AN45 on-time and the more efficient the converter will be since the base current is not delivered to the load. Also, as more base current is required, it becomes more difficult for the DCDRV and DCFF pins to switch the transistor off quickly, which further decreases efficiency. Practically, Q7 gain should be around 100 at peak inductor current ...
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... From Equation BAT From Equation 3: I AVG The output power equation becomes pin SDCL and OUT BAT = 2.9 W Rev. 0.5 AN45 ( ) VCC VBE + R28 ------------------------------------ - = 148 µA V CLAMP R29 -------------------- - = 148 µA is the clamping voltage for VBAT. from Equation 1: × 2 ...
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... AN45 Step 2: Selecting Output Power Requirement Set up for power optimization in the active off-hook mode Register 65 = LIM ( Register 66 = BJTBIAS ( Track 1 Register Register Register 66 OV From Equation 0 BAT LIM BJTBIAS LIM = 24.5 mA From track 1 Equation 6: ...
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... Figure 6. R16, R17, Q7, and Q8 are eliminated. The M1 MOSFET is the main power-switching component in this design. The Si321xM version of the ProSLIC is used to directly drive the M1 MOSFET using the DCFF pinout. = 56K = 1.176 A ) 0.5 Ω = Rev. 0.5 AN45 Voltage Voltage Parameter Rating V – 1.5 98 150 CEO ...
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... AN45 Si3210M R19 RMONH 8 SDCH R20 RMONL 9 SDCL 33 DCFF C27 470pF 34 DCDRV M1 2 R23 200k Q9 VCC 2222 R28* R29* VBAT Figure 6. Transformer DC-DC Converter All relevant design equations for the inductor dc-dc converter are applied in the same manner for the transformer dc-dc converter except for the following equations ...
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... Steps 7 and 8 are the same step 9, use the voltage rating for M1 instead of Q1. The voltage parameter for follows Other components in the circuit that are not discussed above should use the component values recommended in Figure 6. 2.54 4.17 Rev. 0.5 AN45 DSS ------------- - VDC V = – N ...
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... AN45 Document Change List Revision 0.4 to Revision 0.5 " Equation 6 Changed RLINE to RLOOPMAX. ! " “In the Off-Hook State” Updated text. ! " “Step 1: Define the Output Requirement” Added +160 to first equation. ! " “Step 2: Selecting Output Power Requirement” Added +160 to last equation. ...
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... Notes: Rev. 0.5 AN45 13 ...
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... AN45 Contact Information Silicon Laboratories Inc. 4635 Boston Lane Austin, TX 78735 Tel: 1+(512) 416-8500 Fax: 1+(512) 416-9669 Toll Free: 1+(877) 444-3032 Email: productinfo@silabs.com Internet: www.silabs.com The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice. ...