HV440DB2 Demo Board by Jimes Lei, Applications Engineering Manager

Transcription

1 Demo Board by Jimes Lei, Applications Engineering Manager Introduction The Supertex HV440 is a power-efficient, switch-mode ring generator IC requiring minimal external components. The demo board contains all the circuitry necessary to drive a 20 REN (North American) ringer load. Simply connect power supplies, ringer load, and enable input as shown below. For a more detailed description on using the HV440, please refer to Application Note AN-H37. Specifications Ringing Frequency 20Hz ±2Hz Ringing Amplitude 62V RMS ± Ringer THD <0% Output Offset -48V DC ±4V (using a 5V ± supply) Max Ringer Load 20 REN (North American) Board Layout and Connections + blue red black yellow J Vnn Gnd N/C Vpp L J2 Ringout white black green Ringer Output and Supplies is +56.5V ±. is -53V ±. The voltage difference between these two supplies must not exceed 220 volts. Current draw from each supply is typically 70mA. Output filter capacitance of these supplies must be at least 200µF. The supply must be powered up before the and supplies. See the section on supply sequencing on the next page. +5 Volt Supply Required tolerance is ±. Current draw is less than 2mA. Ringer output offset is referenced to the 5 volt supply and varies 9.6 volts for every volt change in the supply. This input enables/disables the ringer output. A logic low () turns the output ON, while a high (5V) turns the output OFF. The enable pin must not be left floating. When OFF, the output is in a high impedance state. The output must be enabled only after the supplies are stable. Ringer Output Connect the ringer load between this output and ground. The load need not be AC coupled, although current draw from the supply will increase to about 40mA with a DC coupled load, due to the -48VDC output offset. 02/02/99 Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For complete liability information covering this and other Supertex products, refer to the Supertex 998 Databook.

2 Supply Sequencing The supply must always be powered up before the and supplies. In addition, the input should be ON only after the supplies have stabilized, and should be OFF before the supplies are powered-down. The following sequencing is recommended. Other Ringing Frequencies By simply changing two resistors, the supplied circuit may be modified to provide ringing frequencies other than 20Hz. The following table lists the resistors to change for some standard ringing frequencies. Please refer to the board layout and connection diagram at the beginning of this note for component locations. V DD ENABLE +56.5V -53V OFF ON Ringing Frequency R4, 2 Accuracy 6.7Hz 243kΩ 0.6% 20Hz 205kΩ Hz 62kΩ 0.8% 30Hz 37kΩ -0.7% 33.3Hz 2kΩ.3% 40Hz 02kΩ 0.0% 42Hz 97.6kΩ -0.4% 50Hz 80.6kΩ.3% 54Hz 75.0kΩ 0.8% 5 REN Capability A demo board capable of driving 5 RENs (HV440DB) is also available from Supertex. However, the supplied board () can be modified to provide 5 RENs, as outlined below. Refer to the board layout and connection diagram at the beginning of this note for component locations.. Add a jumper on the R20 pads 2. Remove and 3. Change L to 0mH (20mA rating)* 4. Change to 220nF (20DC rating) 5. Change C5 to 680pF 6. Change and to 3.9Ω (/8W rating) 7. Ensure that the and supplies are capable of 30mA and have at least 47µF of output capacitance * Not all inductors behave similarly, especially at higher frequencies. The recommended inductor is a Delevan L-D. 60Hz 68.kΩ -0.% 66.7Hz 60.4kΩ.3% Values for other frequencies may be determined from f ring = (2πRC) - where R=R4= and C=C3=C4. 2 Not including component tolerances. Output Ripple Reduction As supplied, the has less than V RMS of output ripple. To obtain even lower ripple, may be increased. However, do not exceed 2µF, as distortion of the ringing signal may result. The capacitor should be rated for 20DC, nonpolarized. 2

3 C 0nF R 0.0K R2.82K 4.87K 5. /4 U C2 0nF R9 0.0K R0 5.K Unless noted otherwise: All resistors /8W, % All capacitors 5, 0% R6.0K C3 R4 R 3.32K R2.00K /4 U2 R3 0.0K C5 330pF R7 576 Schematic D D2 C6 0nF R4.0K R6.00M.50K 0.0K /4 U /4 U C V DD C0 2.2 F /4 U2 R7.0K 6 N IN 7 EN 5 mode 4 P IN Logic Control 3 Gnd 2 P Gnd 5V=OFF =ON HV440 U3 Driver V Psen V Pgate HV OUT V Ngate Driver V Nsen 9 V NN2 V PP F C7 0. F.2 TP2522N8 TN2524N8 680pF.2 J2 4.7 F 0 D3 BAS2.0mH L D4 BAS2 4.7 F 25 Output J Sine Wave Ring Output 0.47 F 25 VNN N/C VPP 3

4 Desig R R2 R3 R4 R6 R7 R9 R0 R R2 R3 R4 R6 R7 C C2 C3 C4 C5 C6 C7 C0 L D-D2 D3 D4 U U2 U3 Description Demo Board BOM Value Tol Rating 0.0K % /8W.82K % /8W 4.87K % /8W % /8W % /8W.00K % /8W 576 % /8W.50K % /8W 0.0K % /8W 5.K % /8W 3.32K % /8W.00K % /8W 0.0K % /8W.0K % /8W.00M % /8W 0K /8W K /8W. 2 /8W. 2 /8W Surface mount film capacitor Surface mount film capacitor NPO ceramic chip capacitor Metallized polyester film capacitor Tantalum electrolytic chip capacitor Aluminum electrolytic capacitor Aluminum electrolytic capacitor Inductor 0nF 0% 5 0nF 0% pF 5 0nF 0% 5 0.µ F 0% 5 0.µ F 0% µ F 0% µ F 4.7µ F 0 4.7µ F pF 0% 5.0mH 0% 50mA P-channel MOSFET T P2522N8 22, 0.75A N-channel MOSFET T N2524N8 24,.0A Diode array, fast recovery B AV99 7 Diode, fast recovery B AS2 25 Diode, fast recovery B AS2 25 Quad operational amplifier IC Dual high speed comparator IC High Voltage Ring Generator IC L M2902M L M2903M H V440WG 02/02/ Bordeaux Drive, Sunnyvale, CA TEL: (408) FAX: (408)

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