Electronic Components Datasheet Search |
|
MAX3228EEBV-T Datasheet(PDF) 8 Page - Maxim Integrated Products |
|
MAX3228EEBV-T Datasheet(HTML) 8 Page - Maxim Integrated Products |
8 / 16 page AutoShutdown The MAX3228E/AE and MAX3229E/AE achieve a 1µA supply current with Maxim’s AutoShutdown feature, which operates when FORCEON is low and FORCEOFF is high. When these devices sense no valid signal lev- els on all receiver inputs for 30µs, the on-board charge pump and drivers are shut off, reducing VCC supply current to 1µA. This occurs if the RS-232 cable is dis- connected or the connected peripheral transmitters are turned off. The device turns on again when a valid level is applied to any RS-232 receiver input. As a result, the system saves power without changes to the existing BIOS or operating system. Table 3 and Figure 2c summarize the MAX3228E/AE and MAX3229E/AE operating modes. FORCEON and FORCEOFF override AutoShutdown. When neither con- trol is asserted, the IC selects between these states automatically, based on receiver input levels. Figures 2a, 2b, and 3a depict valid and invalid RS-232 receiver levels. Figures 3a and 3b show the input levels and tim- ing diagram for AutoShutdown operation. A system with AutoShutdown may need time to wake up. Figure 4 shows a circuit that forces the transmitters on for 100ms, allowing enough time for the other system to realize that the MAX3228E/AE and MAX3229E/AE are active. If the other system transmits valid RS-232 signals within that time, the RS-232 ports on both systems remain enabled. When shut down, the device’s charge pumps are off, V+ is pulled to VCC, V- is pulled to ground, and the transmitter outputs are high-impedance. The time required to exit shutdown is typically 100µs (Figure 3b). FORCEON and FORCEOFF In case FORCEON and FORCEOFF are inaccessible, these pins have 60kΩ (typ) pullup resistors connected to VL (Table 2). Therefore, if FORCEON and FORCEOFF are not connected, the MAX3228E/AE and MAX3229E/AE will always be active. Pulling these pins to ground will draw current from the VL supply. This current can be cal- culated from the voltage supplied at VL and the 60kΩ (typ) pullup resistor. VL Logic Supply Input Unlike other RS-232 interface devices, where the receiver outputs swing between 0 and VCC, the ±15kV ESD-Protected +2.5V to +5.5V RS-232 Transceivers in UCSP and WLP 8 _______________________________________________________________________________________ Figure 3. AutoShutdown Trip Levels V- VCC 0 V+ 0 VCC tINVL tWU INVALID REGION RECEIVER INPUT VOLTAGE (V) INVALID OUTPUT (V) tINVH TRANSMITTERS ENABLED, INVALID HIGH AUTOSHUTDOWN, TRANSMITTERS DISABLED, 1 μA SUPPLY CURRENT, INVALID LOW TRANSMITTERS ENABLED, INVALID HIGH a) b) -2.7V -0.3V +2.7V +0.3V 0 INDETERMINATE INDETERMINATE Figure 4. AutoShutdown with Initial Turn-On to Wake Up a Mouse or Another System FORCEON MASTER SHDN LINE 0.1 μF1MΩ FORCEOFF MAX3228E/AE MAX3229E/AE POWER- MANAGEMENT UNIT PIN NAME POWER-ON DEFAULT MECHANISM FORCEON High Internal pullup FORCEOFF High Internal pullup Table 2. Power-On Default States |
Similar Part No. - MAX3228EEBV-T |
|
Similar Description - MAX3228EEBV-T |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | 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 |