 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LT3689HMSE-TRPBF Datasheet(PDF) 9 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
LT3689HMSE-TRPBF Datasheet(HTML) 9 Page - Linear Technology |
|
|
9 / 32 page  LT3689/LT3689-5 9 3689fa PIN FUNCTIONS BST: The BST pin is used to provide drive voltage higher than the input voltage to the internal NPN power switch. VIN: The VIN pin supplies current to the LT3689’s internal circuitry and to the internal power switch and must be locally bypassed. SW: The SW pin is the output of the internal power switch. Connect this pin to the inductor, catch diode and boost capacitor. DA: Tie the DA pin to the anode of the external catch Schottky diode. If the DA pin current exceeds 1.2A, which could occur in an overload or short-circuit condi- tion, switching is disabled until the DA pin current falls below 1.2A. EN/UVLO: The EN/UVLO pin is used to put the LT3689 in shutdown mode. Pull the pin below 0.3V to shut down the LT3689. The 1.26V threshold can function as an accurate undervoltage lockout (UVLO), preventing the regulator from operating until the input voltage has reached the programmed level. FB: The LT3689 regulates the feedback pin to 0.800V. Con- nect the feedback resistor divider tap to this pin. For the fixed LT3689-5 output, this pin can be used to connect a phase lead capacitor between the OUT pin and FB pin to optimize transient response. WDE: Watchdog Timer Enable Pin. This pin disables the watchdog timer if the WDE voltage exceeds 1V. WDO is high in this condition. W/T: Setting W/T low puts the LT3689 watchdog timer into window mode. If two or more negative edges occur on WDI before the watchdog lower boundary (tWDL) period expires, or no negative edge occurs within the watchdog upper boundary (tWDU) period, the part will set WDO low. If W/T is set high, the part will only set WDO low if no transition occurs within the watchdog upper boundary period. WDI: Watchdog Timer Input Pin. This pin receives the watchdog signal from a microprocessor. If the appropriate signal is not received, the part will pulse WDO low for a period equal to the reset timeout period. The watchdog timer is disabled until the WDO pin goes high again. RST: Active low, open collector logic output with a weak pull-up to VOUT. After VOUT rises above 90% of its pro- grammed value, the reset remains asserted for the period set by the capacitor on the CPOR pin. WDO: Active low, open collector logic output with weak pull-up to VOUT. WDO pulls low if the WDE is enabled and the microprocessor fails to drive the WDI pin of the LT3689 with an appropriate signal. CWDT: Watchdog Timer Programming Pin. Place a capa- citor (CWDT) between this pin and ground to adjust the watchdog upper and lower boundary period. To determine the watchdog upper boundary period, and the lower bound- ary period, use the following equations: tWDU = 18.2 • CWDT (watchdog upper boundary period) tWDL = 0.588 • CWDT (watchdog lower boundary period) tWDU and tWDL are in ms and CWDT is in nF. As an example, a 47nF capacitor will generate an 855ms watchdog upper boundary period and a 27.6ms watchdog lower boundary period. CPOR: Reset Delay Timer Programming Pin. Attach an external capacitor (CPOR) to GND to set a reset delay time of 2.3ms/nF. RT: Sets the Internal Oscillator Frequency. Tie a 31.6k resis- tor from RT to GND for a 500kHz switching frequency. SYNC: Drive the SYNC pin with a logic level signal with positive and negative pulse widths of at least 80ns. The RT resistor should be chosen to set the LT3689 switching frequency at least 20% below the lowest synchronization input frequency. OUT: The OUT pin supplies current to the internal circuitry when OUT is above 3V, reducing input quiescent current. The internal Schottky diode is connected from OUT to BST, providing the charging path for the boost capacitor. For the LT3689-5, this pin connects to the internal feedback divider that programs the fixed 5V output. GND: Ground. Tie the exposed pad directly to the ground plane. The exposed pad metal of the package provides both electrical contact to ground and good thermal contact to the printed circuit board. The device must be soldered to the circuit board for proper operation. |
Similar Part No. - LT3689HMSE-TRPBF |
|
Similar Description - LT3689HMSE-TRPBF |
|
|
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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
