Moteur de recherche de fiches techniques de composants électroniques |
|
SP6682 Fiches technique(PDF) 5 Page - Sipex Corporation |
|
SP6682 Fiches technique(HTML) 5 Page - Sipex Corporation |
5 / 12 page 5 Date: 5/5/04 SP6682 High Efficiency Charge Pump Regulator for White LEDs © Copyright 2004 Sipex Corporation 0 1 2 3 4 5 6 2.7 3 3.3 3.6 3.9 4.2 Input Voltage (V) 4 LED's @ 30mA 4 LED's @ 15mA PERFORMANCE CHARACTERISTICS: Continued Refer to the typical application circuit, TAMB = 25°C, IO = 60mA unless otherwise specified. 0 1 2 3 020 40 6080 100 Duty Cycle,% 100 Hz 500 Hz General Overview The SP6682 is a current regulated charge pump ideal for converting a Li-Ion battery input for driving white LEDs used in backlighting color displays in cellular phones, PDAs, digital cam- eras and MP3 players. The SP6682’s propri- etary AutoBoost feature enables the IC to auto- matically transition from X1.5 boost mode to X2 boost mode based on battery input voltage for optimal efficiency and performance. The SP6682 is able to efficiently drive up to six 20mA white LEDs in parallel and maintain a constant brightness over a very wide operating voltage range (2.7V to 5.5V). The SP6682 oper- ates with an internal 600kHz clock, enabling the use of small external components. Other fea- tures of SP6682 include PWM dimming control as well as complete input/out disconnect in shutdown. In shut down mode the IC draws less than 1.5 µA current. The output regulation is achieved by sensing the voltage at the feedback pin and modulating the switcher between the charge pump and output capacitor. Theory of Operation The SP6682 regulated charge pump block dia- gram consists of four main blocks (Voltage Reference, Mode Control, Clock Manager, Start- up and Charge-Pump Switches) and two com- parators (VMODE Comparator and VOUT Com- parator). 1) Voltage Reference. This block provides the 306mV and 1.25V reference voltages needed for the two comparators. 2) Mode Control. An external voltage divider connected to the VMODE pin will define an input voltage to the mode comparator which sets the logic state of the mode selection outputs to the X2 or X1.5 modes. VMODE is compared to a 1.25V bandgap voltage. For example, if one makes a 158K/100K divider, the mode will change at 2.58 x 1.25 V =3.23V. A comparator- based cycle by cycle regulation ensures that no mode change occurs during cycles. 3) Clock Manager. An internal 600 kHz clock is generated in this block. Depending on the mode control, the appropriate clock phasing is generated here and sent to the start-up and charge-pump switches block. 4) Start-up and Charge Pump Switches. Dur- ing start-up, until the reference is established, this block keeps the charge pump inactive. Dur- ing this period the output stays floating, by consequence the charge pump drivers are now referenced to VOUT. Charging of the output will occur (e.g. when VIN is ramped up to 4.2V, VOUT ramps only up to about 3V), but not to the value of VIN, protecting the White LED from experi- Figure 7. Brightness vs. input voltage Figure 8. Brightness vs duty cycle OPERATION |
Numéro de pièce similaire - SP6682 |
|
Description similaire - SP6682 |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants 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 |