Electronic Components Datasheet Search |
|
LTC1142HV Datasheet(PDF) 8 Page - Linear Technology |
|
LTC1142HV Datasheet(HTML) 8 Page - Linear Technology |
8 / 20 page 8 LTC1142/LTC1142L/LTC1142HV FU CTIO AL DIAGRA OPERATIO The LTC1142 series consists of two individual regulator blocks, each using current mode, constant off-time archi- tectures to synchronously switch an external pair of complementary power MOSFETs. The two regulators are internally set to provide output voltages of 3.3V and 5V for the LTC1142. The LTC1142HV-ADJ/LTC1142L-ADJ are configured to provide two user selectable output voltages, each set by external resistor dividers. Operating fre- quency is individually set on each section by the external capacitors at CT, Pins 11 and 25. The output voltage is sensed by an internal voltage divider connected to Sense –, Pin 28 (14) (LTC1142) or external divider returned to VFB, Pin 2 (16) (LTC1142-ADJ). A voltage comparator V and a gain block G compare the divided output voltage with a reference voltage of 1.25V. To optimize efficiency, the LTC1142 series automatically switches between two modes of operation, Burst Mode and continuous mode. The voltage comparator is the primary control element when the device is in Burst Mode operation, while the gain block controls the output voltage in continuous mode. During the switch “ON” cycle in continuous mode, current comparator C monitors the voltage between Pins 1 (15) and 28 (14) connected across an external shunt in series with the inductor. When the voltage across the shunt reaches its threshold value, the PDrive output is switched to VIN, turning off the P-channel MOSFET. The timing capacitor connected to Pin 25 (11) is now allowed to discharge at a rate determined by the off-time controller. The discharge current is made proportional to the output voltage [measured by Pin 28 (14)] to model the inductor current, which decays at a rate that is also proportional to the output voltage. While the timing capacitor is discharg- ing, the NDrive output goes to VIN,turningontheN-channel MOSFET. When the voltage on the timing capacitor has discharged past VTH1, comparator T trips, setting the flip-flop. This causes the NDrive output to go low (turning off the N-channel MOSFET) and the PDrive output to also go low (turning the P-channel MOSFET back on). The cycle then repeats. Refer to Functional Diagram Only one regulator block shown. Pin numbers are for 3.3V (5V) sections for LTC1142/LTC1142HV, and VOUT1 (VOUT2) for LTC1142L-ADJ/LTC1142HV-ADJ. – + – + REFERENCE 24(10) 23(9) 6(20) 4(18) 2(16) PGND NDRIVE PDRIVE VIN – + V – + C 25mV TO 150mV + – 1(15) VOS 26(12) 2(16) SHUTDOWN INT VCC 1.25V 5pF G 27(13) ITH Q R S VIN SENSE– OFF-TIME CONTROL 25(11) 13k – + S SLEEP VTH1 CT T SENSE+ VTH2 PIN NUMBERS FOR LTC1142, LTC1142HV PIN NUMBERS FOR LTC1142L-ADJ LTC1142HV-ADJ LTC1142-ADJ 3(17) LTC1142L-ADJ LTC1142HV-ADJ 4(18) LTC1142L-ADJ LTC1142HV-ADJ 2(16) LTC1142L-ADJ, LTC1142HV-ADJ: 5(19) LTC1142L-ADJ LTC1142HV-ADJ 3(17) 3(17) SGND 100k 28(14) SENSE– 1142 BD NC/ADJ |
Similar Part No. - LTC1142HV |
|
Similar Description - LTC1142HV |
|
|
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 |