Electronic Components Datasheet Search |
|
MAX16821C Datasheet(PDF) 11 Page - Maxim Integrated Products |
|
MAX16821C Datasheet(HTML) 11 Page - Maxim Integrated Products |
11 / 25 page High-Power Synchronous HBLED Drivers with Rapid Current Pulsing ______________________________________________________________________________________ 11 Current-Error Amplifier The MAX16821A/MAX16821B/MAX16821C include a transconductance current-error amplifier with a typical gm of 550µS and 320µA output sink and source capa- bility. The current-error amplifier output (CLP) is con- nected to the inverting input of the PWM comparator. CLP is also externally accessible to provide frequency compensation for the inner current regulation loop (Figure 2). Compensate CEA so the inductor current negative slope, which becomes the positive slope to the inverting input of the PWM comparator, is less than the slope of the internally generated voltage ramp (see the Compensation section). In applications without syn- chronous rectification, the LED driver can be turned off and on instantaneously by shorting or opening the CLP to ground. PWM Comparator and R-S Flip-Flop An internal PWM comparator sets the duty cycle by comparing the output of the current-error amplifier to a 2VP-P ramp signal. At the start of each clock cycle, an R-S flip-flop resets and the high-side driver (DH) turns on if MODE is connected to SGND, and DL turns on if MODE is connected to VCC. The comparator sets the flip-flop as soon as the ramp signal exceeds the CLP voltage, thus terminating the ON cycle. See Figure 3. Differential Amplifier The differential amplifier (DIFF) allows LED current sens- ing (Figure 2). It provides true-differential LED current sensing, and amplifies the sense voltage by a factor of 1 (MAX16821A), 6 (MAX16821B), and 20 (MAX16821C), while rejecting common-mode voltage errors. The VEA provides the difference between the differential amplifier output (DIFF) and the desired LED current-sense volt- age. The differential amplifier has a bandwidth of 1.7MHz (MAX16821A), 1.6MHz (MAX16821B), and 550kHz (MAX16821C). The difference between SENSE+ and SENSE- is regulated to +0.6V (MAX16821A), +0.1V (MAX16821B), or +0.03V (MAX16821C). PWM COMPARATOR CLK SHDN RAMP IN CSP CLP CSN MODE = GND AV = 34.5 60mV gm = 550µS SQ RQ PEAK-CURRENT COMPARATOR BST DH LX VDD DL PGND Figure 3. MAX16821A/MAX16821B/MAX16821C Phase Circuit |
Similar Part No. - MAX16821C |
|
Similar Description - MAX16821C |
|
|
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 |