Electronic Components Datasheet Search |
|
SP240A Datasheet(PDF) 7 Page - Sipex Corporation |
|
SP240A Datasheet(HTML) 7 Page - Sipex Corporation |
7 / 17 page 7 Date: 8/3/04 + 5V Powered Multi-Channel RS-232 Drivers/Receivers © Copyright 2004 Sipex Corporation standards [EIA RS-232–D 2.1.7, Paragraph (5)]. The transitionoftheloadedoutputfromV OL to VOH clearly meets the monotonicity requirements of the standard [EIA RS-232–D 2.1.7, Paragraphs (1) & (2)]. Receivers The receivers convert RS-232 input signals to in- verted TTL signals. Since the input is usually from a transmission line, where long cable lengths and sys- tem interference can degrade the signal, the inputs have a typical hysteresis margin of 500mV. This ensures that the receiver is virtually immune to noisy transmission lines. The input thresholds are 0.8V minimum and 2.4V maximum, again well within the ±3V RS-232 re- quirements. The receiver inputs are also protected against voltages up to ±30V. Should an input be left unconnected, a 5k Ω pulldown resistor to ground will commit the output of the receiver to a high state. In actual system applications, it is quite possible for signals to be applied to the receiver inputs before power is applied to the receiver circuitry. This occurs, for example, when a PC user attempts to print, only to realize the printer wasn’t turned on. In this case an RS-232signalfromthePCwillappearonthereceiver input at the printer. When the printer power is turned on, the receiver will operate normally. All series devices are fully protected. Again, to facilitate use in “real-world” applications, the receiver outputs can be tri–stated by bringing the ENABLE (EN) pin high, with the driver remaining full active. Charge Pump ThechargepumpsectionoftheSP230Aseriesallows the circuit to operate from a single +5V, ±10%power S1 GND V CC + V+ = 2V CC + V CC S2 S3 S4 C1 C3 INTERNAL OSCILLATOR Figure 1. Charge Pump Voltage Doubler supply by generating the required operating voltages internal to the devices. The charge pump consists of two sections — 1) a voltage doubler and 2) a voltage inverter. As shown in Figure 1, an internal oscillator triggers the charge accumulation and voltage inversion. The voltage doubler momentarily stores a charge on capacitor C 1 equal to VCC, reference to ground. During the next transition of the oscillator this charge is boot–strapped to transfer charge to capacitor C 3. The voltage across C 3 is now from VCC to V +. In the inverter section (Figure 2), the voltage across C 3 is transferred to C2 forcing a range of 0V to V+ across C 2. Boot–strapping of C2 will then transfer charge to C 4 to generate V -. The values of the capacitors are somewhat non-critical and can be varied, however the performance will be affected. As C 3 and C4 are reduced, higher levels of ripple will appear. Lower values of C 1 and C2 will increase the 10.5 10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 05 10 15 20 25 30 35 40 V- I (mA) OUT V =5.5V CC V =5V CC V =4.5V CC 10.5 10.0 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 05 10 15 20 25 30 35 40 V+ I (mA) OUT V =5.5V CC V =5V CC V =4.5V CC Charge Pump Output Loading versus VCC; a) V+; b) V– a) b) |
Similar Part No. - SP240A |
|
Similar Description - SP240A |
|
|
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 |