Electronic Components Datasheet Search |
|
A6261 Datasheet(PDF) 9 Page - Allegro MicroSystems |
|
A6261 Datasheet(HTML) 9 Page - Allegro MicroSystems |
9 / 15 page Protected LED Array Driver A6261 9 Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com Application Information Power Dissipation The most critical design considerations when using a linear regu- lator such as the A6261 are the power produced internally as heat and the rate at which that heat can be dissipated. There are three sources of power dissipation in the A6261: • The quiescent power to run the control circuits • The power in the reference circuit • The power due to the regulator voltage drop The elements relating to these dissipation sources are illustrated in figure 4. Quiescent Power The quiescent power is the product of the quiescent current, IINQ, and the supply voltage, VIN, and is not related to the regulated current. The quiescent power, PQ, is there- fore defined as: PQ = VIN × IINQ (4) Reference Power The reference circuit draws the reference current from the supply and passes it through the reference resis- tor to ground. The reference current is 8% of the output current on any one active output. The reference circuit power is the prod- uct of the reference current and the difference between the supply voltage and the reference voltage, typically 1.2 V. The reference power, PREF, is therefore defined as: PREF = RREF (VIN – VREF) × VREF (5) Regulator Power In most application circuits the largest dis- sipation will be produced by the output current regulators. The power dissipated in each current regulator is simply the product of the output current and the voltage drop across the regulator. The total current regulator dissipation is the sum of the dissipa- tion in each output regulator. The regulator power for each output is defined as: PREGx = (VIN – VLEDx ) × ILEDx (6) where x is 1, 2, 3, or 4. Note that the voltage drop across the regulator, VREG , is always greater than the specified minimum drop-out voltage, VDO. The output current is regulated by making this voltage large enough to provide the voltage drop from the supply voltage to the total forward voltage of all LEDs in series, VLED. The total power dissipated in the A6261 is the sum of the qui- escent power, the reference power, and the power in each of the four regulators: PDIS = PQ + PREF + PREGA + PREGB + PREGC + PREGD (7) The power that is dissipated in each string of LEDs is: PLEDx = VLEDx × ILEDx (8) where x is A, B, C, or D, and VLEDx is the voltage across all LEDs in the string. A6261 LAx ILAx IINQ IREF VIN GND IREF RREF VREF VLED VREG VIN Figure 4. Internal power dissipation sources. |
Similar Part No. - A6261 |
|
Similar Description - A6261 |
|
|
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 |