 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LM5005MHX Datasheet(PDF) 11 Page - National Semiconductor (TI) |
|
|
||||||||||||||||||||||||||||||
LM5005MHX Datasheet(HTML) 11 Page - National Semiconductor (TI) |
|
|
11 / 21 page  Shutdown / Standby The LM5005 contains a dual level Shutdown (SD) circuit. When the SD pin voltage is below 0.7V, the regulator is in a low current shutdown mode. When the SD pin voltage is greater than 0.7V but less than 1.225V, the regulator is in standby mode. In standby mode the Vcc regulator is active but the output switch is disabled. When the SD pin voltage exceeds 1.225V, the output switch is enabled and normal operation begins. An internal 5µA pull-up current source configures the regulator to be fully operational if the SD pin is left open. An external set-point voltage divider from Vin to GND can be used to set the operational input range of the regulator. The divider must be designed such that the voltage at the SD pin will be greater than 1.225V when Vin is in the desired operating range. The internal 5µA pull-up current source must be included in calculations of the external set-point divider. Hysteresis of 0.1V is included for both the shutdown and standby thresholds. The voltage at the SD pin should never exceed 8V. When using an external set-point divider, it may be necessary to clamp the SD pin to limit its voltage at high input voltage conditions. The SD pin can also be used to implement various remote enable / disable functions. Pulling the UVLO pin below the 0.7V threshold totally disables the controller. If the SD pin voltage is above 1.225V the regulator will be operational. Oscillator and Sync Capability The LM5005 oscillator frequency is set by a single external resistor connected between the RT pin and the AGND pin. The R T resistor should be located very close to the device and connected directly to the pins of the IC (RT and AGND).To set a desired oscillator frequency (F), the neces- sary value for the R T resistor can be calculated from the following equation: The SYNC pin can be used to synchronize the internal oscillator to an external clock. The external clock must be of higher frequency than the free-running frequency set by the R T resistor. A clock circuit with an open drain output is the recommended interface from the external clock to the SYNC pin. The clock pulse duration should be greater than 15 ns. Multiple LM5005 devices can be synchronized together sim- ply by connecting the SYNC pins together. In this configura- tion all of the devices will be synchronized to the highest frequency device. The diagram in Figure 5 illustrates the SYNC input/output features of the LM5005. The internal oscillator circuit drives the SYNC pin with a strong pull-down / weak pull-up inverter. When the SYNC pin is pulled low either by the internal oscillator or an external clock, the ramp cycle of the oscillator is terminated and a new oscillator cycle begins. Thus, if the SYNC pins of several LM5005 IC’s are connected together, the IC with the highest internal clock frequency will pull the connected SYNC pins low first and terminate the oscillator ramp cycles of the other IC’s. The LM5005 with the highest programmed clock frequency will serve as the master and control the switching frequency of the all the devices with lower oscillator frequency. 20161905 FIGURE 3. Sync from External Clock 20161906 FIGURE 4. Sync from Multiple Devices www.national.com 11 |
Similar Part No. - LM5005MHX |
|
Similar Description - LM5005MHX |
|
|
|
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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
