Electronic Components Datasheet Search |
|
SP320 Datasheet(PDF) 5 Page - Exar Corporation |
|
SP320 Datasheet(HTML) 5 Page - Exar Corporation |
5 / 12 page 5 Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (50) 668-707 • www.exar.com SP320_00_092208 phase 4 -Vdd transfer- The fourth phase of the clock connects the negative terminal of C2 to ground and transfers the generated +0V across C2 to C4, the Vdd storage capacitor. Again, simultaneously with this, the positive side of capacitor C is switched to +5V and the negative side is connected to ground, and the cycle begins again. Since both V+ and V- are separately gener- ated from Vcc in a no load condition, V+and V- will be symmetrical. Older charge pump approaches that generate V- from V+ will show a decrease in the magnitude ofV-com- pared to V+ due to the inherent inefficiencies in the design. The clock rate for the charge pump typically operates at 5kHz. The external capaci- tors must be 0.µF with a 6V breakdown rating. shutdown Mode The SP320 can be put into a low power shutdown mode by bringing both TS000 (pin 3)andENV35(pin9)low.Inshutdownmode, the SP320 will draw less than 2mAof supply current. For normal operation, both pins should be connected to +5V. external power supplies For applications that do not require +5V only, external supplies can be applied at the V+ and V- pins. The value of the external supply voltages must be no greater than ±0V. The current drain from the ±0V sup- plies is used for the RS-232 drivers. For the RS-232 driver the current re- quirement will be 3.5mA per driver. It is critical the external power supplies provide a power supply sequence of : +0V, +5V, and then -0V. Applications information TheSP320isasinglechipdevicethatcanim- plement a complete V.35 interface.Three (3) V.35 drivers and three (3) V.35 receivers are used for clock and data signals and four (4) RS-232 (V.28) drivers and four (4) RS-232 (V.28) receivers can be used for the control signals of the interface. The following ex- amples show the SP320 configured in either a DTE or DCE application. +0V a) C 2 + GND GND b) C 2 – –0V Figure . Charge Pump Waveforms capacitors, but uses a four-phase voltage shiftingtechniquetoattainsymmetrical±0V powersupplies.Thecapacitorscanbeaslow as 0.µF with a 6 Volt rating. Polarized or non-polarized capacitors can be used. Figure (a) shows the waveform found on the positive side of capacitor C2, and Figure (b)showsthenegativesideofcapacitorC2. Thereisafree-runningoscillatorthatcontrols the four phases of the voltage shifting. A description of each phase follows. phase 1 -Vss charge storage- During this phase of theclockcycle,thepositivesideofcapactors C and C2 are initially charged to +5V. C+ is then switched to ground and the charge in C- is transferred to C2-. Since C2+ is con- nected to +5V, the voltage potential across capacitor C2 is now 0V. phase 2 -Vss transfer- Phase two of the clock con- nects the negative terminal of C2 to the Vss storage capacitor and the positive terminal of C2 to ground, and transfers the generated -0V to C3. Simultaneously, the positive side of capacitor C is switched to +5V and the negative side is connected to ground. phase 3 -Vdd charge storage- The third phase of the clock is identical to the first phase- the transferred charge in C produces -5V in the negative terminal of C, which is applied to the negative side of capacitor C2. Since C2+ is at +5V, the voltage potential across C2 is +0V. |
Similar Part No. - SP320 |
|
Similar Description - SP320 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |