 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
1308B Datasheet(PDF) 11 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
1308B Datasheet(HTML) 11 Page - Linear Technology |
|
|
11 / 20 page  11 LT1308A/LT1308B 1308abfa APPLICATIONS INFORMATION SHDN PIN The LT1308A/LT1308B SHDN pin is improved over the LT1308. The pin does not require tying to VIN to enable the device, but needs only a logic level signal. The voltage on the SHDN pin can vary from 1V to 10V independent of VIN. Further, floating this pin has the same effect as grounding, which is to shut the device down, reducing current drain to 1 μA or less. LOW-BATTERY DETECTOR The low-battery detector on the LT1308A/LT1308B fea- tures improved accuracy and drive capability compared to the LT1308. The 200mV reference has an accuracy of ±2% and the open-collector output can sink 50 μA.TheLT1308A/ LT1308B low-battery detector is a simple PNP input gain stage with an open-collector NPN output. The negative input of the gain stage is tied internally to a 200mV reference. The positive input is the LBI pin. Arrangement as a low-battery detector is straightforward. Figure 10 details hookup. R1 and R2 need only be low enough in value so that the bias current of the LBI pin doesn’t cause large errors. For R2, 100k is adequate. The 200mV refer- ence can also be accessed as shown in Figure 11. LBO LBI TO PROCESSOR R1 100k R2 100k VIN VBAT LT1308A LT1308B 1308 F10 5V GND 200mV INTERNAL REFERENCE – + R1 = VLB – 200mV 2 μA VIN VBAT LT1308A LT1308B LBI LBO 200k 10 μF GND 10k 1308 F11 2N3906 VREF 200mV + 195 200 205 VLBI (mV) 1308 F12 VLBO 1V/DIV Figure 12. Low-Battery Detector Input/Output Characteristic Figure 10. Setting Low-Battery Detector Trip Point Figure 11. Accessing 200mV Reference A cross plot of the low-battery detector is shown in Figure 12. The LBI pin is swept with an input which varies from 195mV to 205mV, and LBO (with a 100k pull-up resistor) is displayed. START-UP The LT1308A/LT1308B can start up into heavy loads, unlike many CMOS DC/DC converters that derive operat- ing voltage from the output (a technique known as “bootstrapping”). Figure 13 details start-up waveforms of Figure 1’s circuit with a 20 Ω load and VIN of 1.5V. Inductor current rises to 3.5A as the output capacitor is charged. After the output reaches 5V, inductor current is about 1A. In Figure 14, the load is 5 Ω and input voltage is 3V. Output voltage reaches 5V in 500 μs after the device is enabled. Figure 15 shows start-up behavior of Figure 5’s SEPIC circuit, driven from a 9V input with a 10 Ω load. The output reaches 5V in about 1ms after the device is enabled. VOUT 2V/DIV IL1 1A/DIV VSHDN 5V/DIV 1ms/DIV 1308 F13 Figure 13. 5V Boost Converter of Figure 1. Start-Up from 1.5V Input into 20 Ω Load |
Similar Part No. - 1308B |
|
Similar Description - 1308B |
|
|
|
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
