Electronic Components Datasheet Search |
|
MAX16824 Datasheet(PDF) 9 Page - Maxim Integrated Products |
|
MAX16824 Datasheet(HTML) 9 Page - Maxim Integrated Products |
9 / 13 page On-board pass elements minimize the need for external components while providing ±5% LED current accura- cy. Additional features include a +5V (±5%) regulated output with 4mA output current capability and thermal protection. The MAX16824/MAX16825 use a feedback loop to lin- early control the current at each output. The voltage across each sense resistor is regulated to 200mV by the internal feedback loop. The output current is set by selecting the value of RCS. +5V Regulator (REG) The MAX16824/MAX16825 include a fixed +5V output regulator that delivers up to 4mA of load current for auxiliary low power applications throughout the 6.5V to 28V input voltage range. Connect a 1µF compensation capacitor from REG to ground. Thermal Protection The MAX16824/MAX16825 enter a thermal shutdown mode in the event of overheating. When the junction temperature exceeds TJ = +165°C, the internal thermal protection circuit turns off the series pass elements. The MAX16824/MAX16825 recover from thermal shut- down mode when the junction temperature drops by 23°C. The thermal protection does not operate if the regulator (REG) is in a short-circuit condition. 4-Wire Serial Interface (MAX16825) The MAX16825 features a 4-wire serial interface (DIN, CLK, LE, OE) and a data output (DOUT) that allows the use of a microcontroller to write brightness data to the MAX16825. The serial-interface data word length is 3 bits (D0, D1, D2). The functions of the interface inputs are as follows: DIN is the serial-data input, which must be stable when it is sampled by the MAX16825 on the rising edge of CLK. Data shifts in with the MSB first. This means that data bit D2 is clocked in first, followed by 2 more data bits (D1 and finishing with the LSB D0). CLK is the serial-clock input, which shifts data at DIN into the MAX16825’s 3-bit shift register on the rising edge. LE is the latch-enable input that allows the trans- fer of data from the MAX16825’s 3-bit shift register to its 3-bit latch when LE is high (transparent latch) and latches the data on the falling edge of LE (Figure 4). Output enable (OE) provides simultaneous control of the output drivers. Driving OE high places outputs OUT1, OUT2, and OUT3 into a high-impedance mode without altering the contents of the output latches. Driving OE low allows outputs OUT1, OUT2, and OUT3 to follow the state of the output latches. OE is independent of the operation of the serial inter- face. Data can be shifted into the serial-interface shift register and latched regardless of the state of OE. DOUT is the serial-data output that shifts data out from the MAX16825’s 3-bit shift register on the rising edge of CLK. Data at DIN propagates through the shift register and appears at DOUT three clock cycles later. Applications Information Programming the LED Current The MAX16824/MAX16825 use sense resistors to set the output current in each channel. To set the LED current for a particular channel, connect a sense resistor across the corresponding current-sense input (CS_) and GND. For better performance, connect the low side of the cur- rent-sense resistors to the IC’s ground terminal and the high side to the CS_ terminal with short traces. The value of the sense resistor for a given desired current is calcu- lated with the following equation: where VCS_ is 200mV and IOUT_ is ILED (see the Electrical Characteristics table). LED Supply Voltage Considerations For proper operation, the minimum LED supply voltage (applied between the LED string anode and ground) must always be: where VCS_ is the voltage drop across the sense resis- tor RCS_, VFT(MAX) is the total forward voltage of all series connected LEDs and ΔVDO is the maximum dropout voltage of the regulator. Pulse-Width Dimming (MAX16824) The MAX16824 includes pulsed-width current dimming inputs (PWM_) to control the LED brightness. An appli- cation of up to 5kHz signal or less is recommended at PWM_ input for proper operation. PWM_ also functions as an active-high enable input for each output channel. A logic-low at PWM_ turns off OUT_ and a logic-high turns on OUT_. Pulse-Width Dimming (MAX16825) The MAX16825 provides three methods of pulsed-width current dimming. One method of pulse dimming the output channels is to drive OE low while latching a different set of three bits VV V V LED MIN CS FT MAX DO () _ ( ) ≥+ + Δ R VV IA CS CS OUT _ _ _ () () () Ω= High-Voltage, Three-Channel Linear High-Brightness LED Drivers _______________________________________________________________________________________ 9 |
Similar Part No. - MAX16824_09 |
|
Similar Description - MAX16824_09 |
|
|
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 |