MIC3289_0706 MICREL | Alldatasheet

Document overview

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Technical content

Features

  • Single wire combines 16 level logarithmic brightness & shutdown control
  • 16V / 24V OVP options supports up to 4 & 6 WLEDs
  • Start-up in any one of 16 brightness levels
  • Internal Schottky diode
  • 2.5V to 6.5V input voltage
  • 1.2 MHz PWM operation
  • Over 500mA switch current
  • 250mV reference voltage
  • ±5% LED current accuracy
  • <1 µA shutdown current
  • Over temperature protection
  • UVLO
  • Thin SOT23-6L package option
  • 2mm × 2mm leadless MLF ®-8L package option
  • –40 oC to +125oC junction temperature range

Applications

  • White/Blue LED driver for backlighting - Cell phones - PDAs - GPS systems - Digital cameras - Multimedia / MP3 players
  • LED flashlights
  • Constant current power supplies

Micrel, Inc. MIC3289 June 2007 2 M9999-061807 (408) 944-0800 Typical Application MIC3289 2mm×2mm MLF 0.27µF Digital Control White LED Driver with OVP and Digital Control

Ordering Information

Junction Temp. Range Package MIC3289-16YD6 WF16 Adjustable 16V -40°C to 125°C TSOT23-6 MIC3289-24YD6 WF24 Adjustable 24V -40°C to 125°C TSOT23-6 MIC3289-16YML WFA Adjustable 16V -40°C to 125°C 2x2 MLF®-8L MIC3289-24YML WFB Adjustable 24V -40°C to 125°C 2x2 MLF®-8L Pin Configuration FB GND OUT VIN SW 1 6 DC 1OUT VIN DC GND 8G N D SW FB NC TSOT23-6 (D) 2mm × 2mm 8-pin MLF®(ML)

Micrel, Inc. MIC3289 June 2007 3 M9999-061807 (408) 944-0800 Pin Description Pin Number SOT23-6 Pin Number 8-pin MLF® Pin Name Pin Name 6 1 OUT Output and Over Voltage Protection (output) 5 2 VIN Supply (Input): 2.5V to 6.5V for internal circuitry. 4 3 DC Single pin digital control. See diagrams. - 5 N/C No connect (no internal connection to die) 3 6 FB Feedback (Input): Output voltage sense node. Connect the cathode of the LED to this pin. 1 7 SW Switch Node (Input): Internal power BIPOLAR collector. 2 4,8 GND Ground (Return): Ground. - Pad GND Ground (Return): Backside pad.

Micrel, Inc. MIC3289 June 2007 4 M9999-061807 (408) 944-0800 Absolute Maximum Ratings(1) Operating Ratings(2) Package Thermal Impedance Electrical Characteristics(4) TA=25oC, VIN = 3.6V, VOUT = 10V, IOUT = 20mA, unless otherwise noted. Bold values indicate -40°C ≤ TJ ≤ 125°C. Symbol Parameter Condition Min Typ Max Units VIN Supply Voltage Range 2.5 6.5 V VUVLO Under-voltage Lockout 1.8 2.1 2.4 V IVIN Quiescent Current V FB >500mV 1.4 5 mA ISD Shutdown Current (DC pin low ) VDC = 0V for > 2ms. 0.01 1 µA VFB Feedback Voltage (+/-5%) 237 250 263 mV IFB Feedback Input Current V FB = 250mV 450 nA Line Regulation 2.5V ≤ VIN ≤ 4.5V 0.5 % Load Regulation 5mA ≤ IOUT ≤ 20mA 0.5 % DMAX Maximum Duty Cycle 85 90 % ISW Switch Current Limit V IN = 3.6V 500 750 1200 mA VDC DC pin thresholds High Low 1.1 0.4 V DC Pin Hysteresis 20 mV IDC DC Pin Current VDC = 3.6V 5 10 µA tshutdown Shutdown Pulse Width VIN = 2.8V to 5.5V VDC = Low 1260 µs tMODE_UP Count UP mode pulse width VIN = 2.8V to 5.5V VDC = Low 100 160 µs tMODE_DO WN Count Down mode pulse width VIN = 2.8V to 5.5V VDC = Low 420 500 µs tstart_up Turn-on Delay Time V IN = 2.8V to 5.5V 140 µs tprog_low Programming pulse width low VIN = 2.8V to 5.5V 1 32 µs tprog_high Programming pulse width high VIN = 2.8V to 5.5V 1 32 µs tdelay Minimum Delay for mode change VIN = 2.8V to 5.5V VDC = High 140 µs Tprog_setup First Pulse Window for Preprogramming VIN = 2.8V to 5.5V 35 50 µs fSW Oscillator Frequency 1 1.2 1.35 MHz

Micrel, Inc. MIC3289 June 2007 5 M9999-061807 (408) 944-0800 Symbol Parameter Condition Min Typ Max Units VD Schottky Forward Drop I D = 150mA 0.8 1 V IRD Schottky Leakage Current VR = 30V 4 µA VOVP Over Voltage Protection 3289- 16 only (nominal voltage) 13 14 16 V 3289- 24 only (nominal voltage) 21 22.5 24 V Tj Over-Temperature Threshold Shutdown 150 °C Notes: 1. Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not a pply when operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(Max), the junction-to-ambient thermal resistance, θ JA, and the ambient temperature, TA. The maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. 2. This device is not guaranteed to operate beyond its specified operating rating. 3. IC devices are inherently ESD sensitive. Handling precautions required. 4. Specification for packaged product only.

Micrel, Inc. MIC3289 June 2007 6 M9999-061807 (408) 944-0800 Typical Characteristics

Micrel, Inc. MIC3289 June 2007 7 M9999-061807 (408) 944-0800 Functional Characteristics

Micrel, Inc. MIC3289 June 2007 8 M9999-061807 (408) 944-0800 Functional Diagram MIC3289 Block Diagram Functional Description The MIC3289 is a constant frequency, PWM current mode boost regulator. It is composed of an oscillator, slope compensation ramp generator, current amplifier, g m error amplifier, PWM generator, bipolar output transistor, digital interface with D/A converter and Schottky rectifier diode. It features true one-wire digital control that may be used to vary the brightness of the output LEDs and to place the device into shutdown mode. The oscillator generates a 1.2MHz clock which triggers the PWM generator that turns on the output transistor and resets the slope compensation ramp generator. The current amplifier is used to measure the switch current by amplifying the voltage signal from the internal sense resistor. The output of the current amplifier is summed with the output of the slope compensation ramp generator. This summed current- loop signal is fed to one of the inputs of the PWM generator. MIC3289 Block Diagram The g m error amplifier measures the LED current through the external sense resistor and amplifies the error between the detected signal and the reference voltage indicated by the digital interface. The output of the g m error amplifier provides the voltage-loop signal that is fed to the other input of the PWM generator. When the current-loop signal exceeds the voltage-loop signal, the PWM generator turns off the bipolar output transistor. The next clock period initiates the next switching cycle, maintaining the constant frequency current-mode PWM control. The LED current level at maximum brightness is set by the feedback resistor: LEDR 250mV ILED = MIC3289 Digital Interface The MIC3289 incorporates an easy to use single-wire, serial programming interface allowing users to set LED brightness to one of 16 levels spaced in a logarithmic manner. In contrast to other solutions requiring a PWM drive signal to maintain LED brightness, the MIC3289 is “set and forget”, relieving the controlling processor of the constant burden of supplying a drive signal. Additionally, brightness levels can be preset so that LEDs can be turned on at a particular brightness level. State Diagram The MIC3289 logic state flow is depicted in Figure 1 below. Brightness level changes are negative edge triggered while all other state changes require a logic high or low be applied to the DC pin for a specific length of time.

Micrel, Inc. MIC3289 June 2007 12 M9999-061807 (408) 944-0800 External Component Selection The MIC3289 can be used across a wide range of applications. The table below shows recommended inductor and output capacitor values for applications driving 3-6 LEDs in series assuming a 20mA maximum drive current from Li-Ion battery source. Series LEDs L Manufacturer Min C OUT Manufacturer LQH43MN220K03 (Murata) 0603YD225MAT2A (AVX) 22µH NLC453232T-220K (TDK) 2.2µF GRM188R61C225KE15D (Murata) LQH43MN100K03 (Murata) 0603YD334MAT2A (AVX) 10µH NLCV32T-100K-PFR (TDK) 0.33µF GRM188RT1C224KA01D (Murata) LQH43MN4R7K03 (Murata) 4.7µH NLCV32T-4R7M-PFR (TDK) 0.22µF 06036ZD224MAT2A (AVX) LQH43MN220K03 (Murata) 0805YD105MAT (AVX) 22µH NLC453232T-220K (TDK) 1.0µF GRM188R61E105KA12D (Murata) LQH43MN100K03 (Murata) 06033D334MAT2A (AVX) 10µH NLCV32T-100K-PFR (TDK) 0.33µF GRM21BR71E334KA01L (Murata) LQH43MN4R7K03 (Murata) 4.7µH NLCV32T-4R7M-PFR (TDK) 0.27µF VJ0805Y274KXAAT (Vishay) LQH43MN220K03 (Murata) 06033D334MAT2A (AVX) 22µH NLC453232T-220K (TDK) 0.33µF GRM21BR71E334KA01L (Murata) LQH43MN100K03 (Murata) 10µH NLCV32T-100K-PFR (TDK) 0.27µF VJ0805Y274KXAAT (Vishay) LQH43MN4R7K03 (Murata) 5,6 4.7µH NLCV32T-4R7M-PFR (TDK) 0.22µF 06036ZD224MAT2A (AVX)

Micrel, Inc. MIC3289 June 2007 13 M9999-061807 (408) 944-0800 Layout Recommendations Top Bottom

Micrel, Inc. MIC3289 June 2007 14 M9999-061807 (408) 944-0800

Package Information

6-Pin TSOT23 (D)

Micrel, Inc. MIC3289 June 2007 15 M9999-061807 (408) 944-0800 8-Pin MLF™ (ML) MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 US A TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2007 Micrel, Incorporated.

Micrel, Inc. MIC3289 June 2007 16 M9999-061807 (408) 944-0800

Revision History

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