AL8400 /AL8400Q
Document overview
- Manufacturer or author: Diodes Incorporated
- PDF pages: 13
Technical content
Features
- Low Reference Voltage (V FB = 0.2V)
- -40 to +125°C Temperature Range
- 3% Reference Voltage Tolerance at +25°C
- Low Temperature Drift
- 0.2V to 18V Open-Collector Output
- High Power Supply Rejection: (> 45dB at 300kHz)
- AL8400QSE-7 Automotive Grade qualified to AEC-Q100 Grade 1
- SOT353: Available in “Green” Molding Compound (No Br, Sb) Lead-Free Finish; RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. “Green” Device (Note 3) Notes: 1. EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoH S 2) compliant. All applicable RoHS exemptions applied. 2. See http://www.diodes.com for more in formation about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free. 3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds. Typical Applications Circuit OUT FB E1GND RB RSETCL ILED = VREF/RSET CD AL8400 Vcc GND Vcc Green
Document number: DS35115 Rev. 4 - 2 2 of 13 www.diodes.com August 2012 © Diodes Incorporated AL8400 /AL8400Q Pin Descriptions Pin Number Name Function 1 E1 Emitter Connection. Connect to GND. 2 GND Analog Ground. Ground return for reference and amplifier. Connect to E1. 3 V CC Supply Input. Connect a 0.47 μF ceramic capacitor close to the device from VCC to GND. 4 FB Feedback Input. Regulates to 200mV nominal. 5 OUT Output. Connect a capacitor close to device between OUT and GND. See the Applications Information section. Functional Block Diagram Figure 1 Block Diagram Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) Symbol Parameter Rating Unit VCC Supply Voltage Relative to GND 20 V VOUT OUT Voltage Relative to GND 20 V VFB FB Voltage Relative to GND 20 V VE1 E1 Voltage Relative to GND -0.3 to+0.3 V TJ Operating Junction Temperature -40 to 150 °C TST Storage Temperature -55 to 150 °C These are stress ratings only. Operation outside the absolute maximum ratings may cause device failure. Operation at the absolute maximum rating for extended periods may reduce device reliability. Package Thermal Data Package θ JA PDIS TA = +25°C, TJ = +150°C SOT353 400°C/W 310mW
Document number: DS35115 Rev. 4 - 2 3 of 13 www.diodes.com August 2012 © Diodes Incorporated AL8400 /AL8400Q Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.) Symbol Parameter Min Max Units VCC Supply Voltage Range 2.2 18 V VOUT OUT Voltage Range 0.2 18 IOUT OUT Pin Current 0.3 15 mA TA Operating Ambient Temperature Range -40 +125 °C Electrical Characteristics (Note 4) (@TA = +25°C, VCC= 12V, VOUT = VFB, IOUT = 1mA, unless otherwise specified.) Symbol Parameter Conditions Min Typ Max Units FBLOAD Feedback Pin Load Regulation IOUT = 1 to 15mA TA = +25°C 3.1 6 mV TA = -40°C to +125°C 10 FBLINE Feedback Pin Line Regulation VCC = 2.2V to 18V TA = +25°C 0.1 1.5 mV TA = -40°C to +125°C 2 FBOVR Output Voltage Regulation VOUT = 0.2V to 18V, IOUT =1mA (Ref. Figure 1) TA = +25°C 2 mV TA = -40°C to +125°C 3 IFB FB Input Bias Current VCC = 18V TA = +25°C -45 nA TA = -40°C to +125°C -200 0 ICC Supply Current VCC = 2.2V to 18V, IOUT =10mA TA = +25°C 0.48 1 mA TA = -40°C to +125°C 1.5 IOUT(LK) OUT Leakage Current VCC = 18V, VOUT = 18V, VFB =0V TA = +25°C 0.1 µA TA = +125°C 1 ZOUT Dynamic Output Impedance I OUT = 1 to 15mA, f < 1kHz TA = +25°C 0.25 0.4 Ω TA = -40°C to +125°C 0.6 PSRR Power Supply Rejection Ratio f = 300kHz, V AC = 0.3VPP T A = +25°C 45 dB BW Amplifier Unity Gain Frequency TA = +25°C 600 kHz G Amplifier Transconductance TA = +25°C 4500 mA/V Note: 4. Production testing of the device is performed at +25°C. Functional operation of the device and parameters specified over the operating temperature range are guaranteed by design, characterization and process control. Typical Characteristics Load Regulation Line Regulation
Document number: DS35115 Rev. 4 - 2 4 of 13 www.diodes.com August 2012 © Diodes Incorporated AL8400 /AL8400Q Typical Characteristics (cont.) Supply Current with Input Voltage Supply Current with Load Current FB Voltage Change with Temperature FB Input Current with Temperature MOSFET Driving Bipolar Transistor Driving
Document number: DS35115 Rev. 4 - 2 8 of 13 www.diodes.com August 2012 © Diodes Incorporated AL8400 /AL8400Q Application Information (cont.) Bipolar Example – Choosing RB and CL (cont.) RBmin To ensure that the output capability of t he AL8400 is not exceeded at maximum V IN, maximum h FE and minimum V BE, these values should be substituted back into the RB equation to determine the minimum allowable value for RB. hFEmax is about 1200 @ IC = 100mA, and a temperature of +85°C (Figure 5) which results in: 1200 150I min B= = 0.125mA The maximum recommended I OUT for AL8400 is 15mA.The minimum V BE, according to the DNLS320E datasheet graph (Figure 6), is approximately 0.4V at 85°C and assuming VCCmax = 12.6V, then from equation 4 the bias resistor value is: min B max OUT FBmin BEmax CC min B I I V VVR + − −= = 000125 . 0 015 . 0 2 . 0 4 . 0 4 . 8 − −= = 516Ω this is less than 17kΩ and so the AL8400 output current is within its ratings. CL Choosing R B = 11k Ω satisfies the requirements for the AL8400 conformance and sets approximately 1mA in the OUT pin. The required compensation capacitor can therefore be calculated from: F 18 . 0k 11 ms 2CL μ ≈Ω≈ Æ 180nF The value of RSET is VREF/ILED so: Finally, the maximum power dissipation of the external bipolar transistor is: PTOT = I LED x VCEMAX = ILED x (VCC_max – VLED_MIN – VFB) = 0.51W This determines the package choice (θJA) in order to keep the junction temperature of the bipol ar transistor below the maximum value allowed. At a maximum ambient temperature of +60°C the junction temperature becomes T J = T A + PTOT x θJA = 60 + 0.51 x 125 = +123.75°C N-Channel MOSFET as the Pass Element Alternatively, an N-channel MOSFET may be used in the same configuration. The current in R B is then reduced compared to the case in which the bipolar transistor is used. For LED currents up to about 400m A a suitable MOSFET is DMN6068SE in the SOT223 package. The d esign procedure is as follows, referring to Figure 7. Figure 7 Application Circuit Using MOSFET
Document number: DS35115 Rev. 4 - 2 9 of 13 www.diodes.com August 2012 © Diodes Incorporated AL8400 /AL8400Q Application Information (cont.) N-Channel MOSFET as the Pass Element (cont.) The equations (1 and 2) for the bipolar transistor are transformed into: LED circuit path: 5. VCC = (VLED + VDS + VFB) where VFB is approximately the internal reference voltage of 200mV. Control drive circuit path 6. VCC = (VRB + VGS + VFB) The maximum total LED voltage plus the reference voltage determines the minimum supply voltage. Substituting into equation 5 yields: FBDSMINLEDmin CC V V VV + + = The MOSFET DC gate current is negligible, so the bias resistor R B has only to provide the minimum output current of the AL8400. So rearranging equation 6 yields the boundaries for allowable RB values: max OUT FBmin GSmax CC min B I V VVR − −= 8. min OUT FBmax GSmin CC max B I VV VR −−= Where IOUTmax is the AL8400 maximum output current Where I OUTmin is the AL8400 minimum output current Once the value of R B has been determined, somewhere between R Bmax and RBmin – trying to get I OUT close to 1mA for all variations, the value for compensation capacitor, CL, should be calculated. The MOSFET selection is also influenced by the maximum power dissipation PTOT = ILED * (VCC – VLED – VFB) = ILED * VDS Since this determines the package choice (θJA) in order to keep the junction temperature below the maximum value allowed. TJ = TA + PTOT • θJA where TJ(MAX) is the maximum operating junction temperature, TA is the ambient temperature, θJA is the junction to ambient thermal resistance. Low Supply Voltages and MOSFET as Pass Element When driving a single LED at low supply voltages, a low threshold MOSFET or high gain NPN bipolar transistor should be used as the LED driving pass transistor. This is because a standard threshold voltage MOSFET might not have enough Gate-Source voltage to ensure that it is sufficiently enhanced to regulate the LED current. MOSFET Example Choosing RB and CL The driver is required to control 3 series connected LEDs at 200mA ±10% from an 12V ±5% supply. Each LED has a forward voltage of 3V minimum and of 3.6V maximum. Therefore the minimum supply voltage is 11.4V and the maximum LED chain voltage is 10.8V. Rearranging equation 5 (page 9); the minimum voltage drop across the MOSFET is required to be: = −− = × FBmax LEDmin CCDSLED VV V R I V 2 . 0 V 8 . 10 V 4 . 11−−= = 0.4V Æ RDS(ON) ≤ 2Ω We will use the DMN6068SE N-channel MOSFET (Q2) with a maximum R DS(ON) of 100mΩ at VGS = 4.5V.
Document number: DS35115 Rev. 4 - 2 12 of 13 www.diodes.com August 2012 © Diodes Incorporated AL8400 /AL8400Q
Ordering Information
Part Number Package Code Packaging 7” Tape and Reel Automotive Grade Quantity Part Number Suffix AL8400QSE-7 SE SOT353 3000/Tape & Reel -7 Y (Note 5) AL8400SE-7 SE SOT353 3000/Tape & Reel -7 - Note: 5. Qualified to AEC-Q100 Grade 1. Marking Information (1) SOT353 1 2 3 XX Y W X ( Top View ) XX : Identification code W : Week : A~Z : 1~26 week; X : A~Z : Green Y : Year 0~9 a~z : 27~52 week; z represents 52 and 53 week Part Number Package Identification Code AL8400SE-7 SOT353 B4 AL8400QSE-7 SOT353 B4 Package Outline Dimensions (All dimensions in mm.) Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version. SOT353 Dim Min Max A 0.10 0.30 B 1.15 1.35 C 2.00 2.20 D 0.65 Typ F 0.40 0.45 H 1.80 2.20 J 0 0.10 K 0.90 1.00 L 0.25 0.40 M 0.10 0.22 α 0° 8° All Dimensions in mm A M J LD B C H K F
Document number: DS35115 Rev. 4 - 2 13 of 13 www.diodes.com August 2012 © Diodes Incorporated AL8400 /AL8400Q Suggested Pad Layout Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version. IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries rese rve the right to make modifications, enhanc ements, improvements, corrections or ot her changes without further notice to this document and any product descri bed herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or an y product described herein; neither does Di odes Incorporated convey any license under its patent or trademark rights, nor the rights of others. Any Customer or us er of this document or products described herein in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated website, harmless against all damages. Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthoriz ed sales channel. Should Customers purchase or use Diodes Inco rporated products for any unintended or una uthorized application, Customers shall i ndemnify and hold Diodes Incorporated and its representativ es harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings noted herein may also be covered by one or more United States, international or foreign trademarks. LIFE SUPPORT Diodes Incorporated products are specifically not authorized for use as critical component s in life support devices or systems without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein: A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when proper ly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Customers represent that they have all necessary expertise in the safety and regulatory ramifi cations of their life support dev ices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or s ystems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporate d and its representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems. Copyright © 2012, Diodes Incorporated www.diodes.com Dimensions Value (in mm) Z 2.5 G 1.3 X 0.42 Y 0.6 C1 1.9 C2 0.65 X Z Y C2C2 G