UM1665 UNIONSEMI | Alldatasheet
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Technical content
Features
LCD Bias Supply White LED Supply for LCD Backlights Digital Still Cameras PDAs, Organizers and Handheld PCs Cellular Phones Standard 3.3V/5V to 12V Conversion 2.0V to 6.0V Input Voltage Range Adjustable Output Voltage up to 28V 400mA Internal Switch Current Up to 1MHz Switching Frequency 36µA Typical No Load Quiescent Current 1µA Maximum Shutdown Current Internal Soft-Start Available in Tiny SOT23-5 and Thin DFN6 3.0×3.0 with 0.60mm (TYP) Thickness Packages Pin Configurations Top View SW GND FB EN VIN1 3 4 1 2 3 MPHO M: Month Code UM1665S SOT23-5 (Top View) 1VIN GND EN FB NC SW 3 4 1665 XX XX: Week Code UM1665DA TDFN6 3.0×3.0
http://www.union-ic.com Rev.05 Mar.2016 2/15 UM1665
Ordering Information
Part Number Packaging Type Marking Code Shipping Qty UM1665S SOT23-5 PHO 3000pcs/7 Inch Tape & Reel UM1665DA TDFN6 3.0×3.0 1665 3000pcs/13 Inch Tape & Reel Pin Description Pin Number Symbol Function UM1665S UM1665DA 1 6 SW Connect the inductor and the Schottky diode to this pin. This is the switch pin and is connected to the drain of the internal power MOSFET. 2 2 GND Ground 3 4 FB This is the feedback pin of the device. Connect this pin to the external voltage divider to program the desired output voltage. 4 3 EN This is the enable pin of the device. Pulling this pin to ground forces the device into shutdown mode reducing the supply current to less than 1µA. This pin should not be left floating and needs to be terminated. 5 1 VIN Supply Voltage Pin - 5 NC Not Connected Absolute Maximum Ratings Over operating free-air temperature (unless otherwise noted) (Note 1) Symbol Parameter Value Unit VIN Supply Voltage on VIN (Note 2) -0.3 to +7.0 V VFB, VEN Voltages on FB, EN (Note 2) -0.3 to VIN+0.3 V VSW Switch Voltage on SW (Note 2) 30 V PD Continuous Power Dissipation at TA=25°C SOT23-5 0.35 W TDFN6 3.0×3.0 1.4 TJ Operating Junction Temperature -40 to +150 °C TSTG Storage Temperature Range -65 to +150 °C TL Maximum Lead Temperature for Soldering 10 Seconds +260 °C Note 1: Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of t he device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute -maximum-rated conditions for extended periods may affect device reliability. Note 2: All voltage values are with respect to network ground terminal.
Note 3: Refer to application section for further information. Figure 1. UM1665 Function Block Diagram
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Electrical Characteristics
(VIN=2.4V, EN=VIN, CIN=4.7μF, COUT=1μF, L=10 μH, TA=-40°C to 85°C, typical values are at TA=25°C, unless otherwise noted) Symbol Parameter Test Conditions Min Typ Max Unit SUPPLY CURRENT VIN Input Voltage Range 2.0 6.0 V IQ Operating Quiescent Current IOUT=0mA, not switching, VFB=1.3V 36 70 μA ISD Shutdown Current EN=GND 0.1 1 μA VUVLO Under-Voltage Lockout Threshold 1.5 1.8 V ENABLE VIH EN High Level Input Voltage 1.3 V VIL EN Low Level Input Voltage 0.4 V IL EN Input Leakage Current EN=GND or VIN 0.1 1 μA POWER SWITCH AND CURRENT LIMIT VSW Maximum Switch Voltage 28 V tON Maximum On Time 4 6 7.5 μs tOFF Minimum Off Time 250 400 550 ns RDS(ON) MOSFET On Resistance VIN=2.4V, ISW=50mA 750 1200 mΩ MOSFET Leakage Current VSW=28V 1 10 μA ILIM MOSFET Current Limit 350 400 500 mA OUTPUT VOUT Adjustable Output Voltage Range VIN 28 V VREF Internal Voltage Reference 1.233 V IFB Feedback Input Bias Current VFB=1.3V 1 μA VFB Feedback Trip Point Line Regulation (Note 4) 2.0V≤VIN≤6.0V, VOUT=18V, ILOAD=10mA 0.05 %/V Load Regulation (Note 4) VIN=2.4V, VOUT=18V, 0mA<IOUT<25mA 0.15 %/mA Note 4: The line and load regulation depend on the external component selection.
http://www.union-ic.com Rev.05 Mar.2016 5/15 UM1665 Operation The UM1665 features a constant off -time control scheme. Operation can be best understood by referring to the function block diagram. The converter monitors the output voltage, and as soon as the feedback voltage falls below the referenc e voltage of typically 1.233 V , the internal switch turns on and the current ramps up. The switch turns off as soon as the inductor current reaches the internally set peak current of typically 400mA. The second criteria that turns off the swi tch is the maximum on-time of 6µs (typical). This is just to limit the maximum on -time of the converter to cover for extreme conditions. As the switch is turned off the external Schottky diod e is forward biased delivering the current to the output. The switch remains o ff for a minimum of 400 ns (typical), or until the feedback voltage drops below the reference voltage again. Using this PFM peak current control scheme the converter operates in d iscontinuous conduction mode (DCM) where the switching frequency depends on the output current, which results in very high efficiency over the entire load current range. Peak Current Control The internal switch turns on until the inductor current reache s the typical dc current limit (ILIM) of 400mA. There is approximately a 100ns delay from the time the current limit is reached and when the internal logic actually turns off the switch. During this 100ns delay, the peak inductor current will increase. Thi s increase demands a larger saturation current rating for the inductor. This saturation current can be approximated by the following equation: ns100L VII IN LIM)TYP(P EAK It means higher input voltage and lower inductor value lead to greater SW peak current. Soft-Start All inductive step -up converters exhibit high inrush current during start -up if no special precaution is made. This can cause voltage drops at the input rail during start up and may result in an unwanted or early system shut down. The UM1665 limits this inrush current by increasing the current limit in two steps from ILIM/4 for 256 cycles to ILIM/2 for the next 256 cycles, and then full current limit. Enable Pulling the enable pin (EN) to ground shuts down the device reducing the shutdown curr ent to 1µA (typical). Since there is a conductive path from the input to the output through the inductor and Schottky diode, the output voltage is equal to the input voltage during shutdown. The enable pin needs to be terminated and should not be left floa ting. Using a small external transistor disconnects the input from the output during shutdown as shown in the figure below.
50 Hz to 10kHz
Figure 4. White LED Supply with Adjustable Brightness Control *A smaller output capacitor value for COUT causes a larger LED ripple. Figure 5. White LED Supply with Adjustable Brightness Control
http://www.union-ic.com Rev.05 Mar.2016 8/15 UM1665 Typical Operating Characteristics (CIN=4.7μF, COUT=1μF, L=10μH, TA=25°C, unless otherwise noted) Efficiency vs. Output Current Efficiency vs. Output Current Efficiency vs. Input Voltage Quiescent Current vs. Input Voltage Feedback Voltage vs. Temperature Switch Current Limit vs. Temperature 60% 65% 70% 75% 80% 85% 90% 1 2 3 4 5 6 Input Voltage (V) Efficiency (%) Io=10mA Io=5mA VOUT=18V, L=10μH 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.1 1 10 100 Output Current (mA) Efficiency (%) VIN=5.0V VIN=3.7V VIN=2.4V VOUT=18V, L=10μH 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.1 1 10 100 Output Current (mA) Efficiency (%) L=10uH L=3.3uH VIN=3.7V, VOUT=18V 1.2 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 -40 -20 0 20 40 60 80 100 Temperature ( ℃) Feedback Voltage (V) VIN=2.4V VIN=3.6V VIN=5.0V 230 250 270 290 310 330 350 370 390 410 430 -40 -20 0 20 40 60 80 100 Temperature ( ℃) Switch Current Limit (mA) VIN=5.0V 1 2 3 4 5 6 Input Voltage (V) Quiescent Current (uA) TA=-30℃ TA=25℃ TA=85℃ VIN=5.0V VIN=3.7V VIN=2.4V L=10μH L=3.3μH IOUT=10mA IOUT=5mA TA= -30°C TA=+25°C TA=+85°C VIN=2.4V VIN=3.6V VIN=5.0V
http://www.union-ic.com Rev.05 Mar.2016 9/15 UM1665 Typical Operating Characteristics (Continued) (CIN=4.7μF, COUT=1μF, L=10μH, TA=25°C, unless otherwise noted) Output Voltage vs. Temperature RDS(ON) vs. Temperature RDS(ON) vs. Input Voltage Line Transient Response Load Transient Response Start-up Behavior VIN=2.4V to 3.4V VOUT 100mV/div VOUT=18V, IOUT=10mA IOUT=1mA to 10mA VOUT 100mV/div VIN=3.3V, VOUT=18V VOUT 5V/div VEN 2V/div VIN=3.6V, VOUT=18V, IOUT=10mA 200μs/div 200μs/div 200μs/div Output Voltage vs Temperature 17.00 17.20 17.40 17.60 17.80 18.00 18.20 18.40 18.60 18.80 19.00 -40 -20 0 20 40 60 80 100 Temperature(℃) Output Voltage (V) VIN=5.0V, IOUT=10mA 300 400 500 600 700 800 900 1000 1100 -40 -20 0 20 40 60 80 100 Temperature ( ℃) Static Drain-Source on-state Resistance (mΩ) 300 400 500 600 700 800 900 1000 1100 1 2 3 4 5 6 Input Voltage (V) Static Drain-Source on-state Resistance (mΩ) VIN=3.6V
http://www.union-ic.com Rev.05 Mar.2016 10/15 UM1665 Applications Information Inductor Selection, Maximum Load Current Since the PFM peak current control scheme is inherently stable, the inductor value does not affect the stability of the regulator. The selection of the inductor together with the nominal load current, input and output voltage of the application determines the switching frequency of the converter. Depending on the application, inductor values between 2.2μH up to 22μH are recommended. The maximum inductor value is determined by the maximum on time of the switch, typically 6μs. The peak current limit of 400mA (typically) should be reached within this 6μs period for proper operation. The inductor value determines the maximum switching frequency of the converter. Therefore, select the inductor value that ensures the maximum switching frequency at the converter maximum load current is not exceeded. The maximum switching frequency is calculated by the following formula: OUTP INOUTminIN max VLI )V(VVfs Where: IP=Peak current as described in the previous peak current control section L=Selected inductor value VINmin=The minimum input voltage when the highest switching frequency occurs If the selected inductor value does not exceed the maximum switching frequency of the converter, the next step is to calculate the switching frequency at the nominal load current using the following formula: LI )VV(VI2)fs(I 2 P DINOUTLOAD LOAD Where: IP=Peak current as described in the previous peak current control section L=Selected inductor value ILOAD=Nominal load current VD=Rectifier diode forward voltage (typically 0.3V) A smaller inductor value gives a higher converter switching frequency, but lowers the efficiency. The inductor value has less effect on the maximum available load current and is only of secondary order. The best way to calculate the maximum available load current under certain operating conditions is to estimate the expected converter efficiency at the maximum load current. This number can be taken out of the efficiency graphs shown in page 6 . The maximum load current can then be estimated as follows: )V(V2 fsLIηI INOUT max P maxLOAD Where: IP=Peak current as described in the previous peak current control section L=Selected inductor value fsmax=Maximum switching frequency as calculated previously η=Expected converter efficiency. Typically 70% to 85% The maximum load current of the conve rter is the current at the operation point where the converter starts to enter the continuous conduction mode. Usually the converter should always operate in discontinuous conduction mode.
http://www.union-ic.com Rev.05 Mar.2016 11/15 UM1665 Last, the selected inductor should have a saturation current that meets the maximum peak current of the converter (as calculated in the peak current control section). Use the maximum value for ILIM for this calculation. Another imp ortant inductor parameter is the dc resistance. The lower the DC resistance, the higher the efficiency of the converter. Setting the Output Voltage The output voltage is calculated as: )2R 1R(1V1.233VOUT For battery powered applications, a high impedance voltage divider should be used with a typical value for R2 of 200kΩ and a maximum value for R1 of 2.2M Ω. Smaller values might be used to reduce the noise sensitivity of the feedback pin. A feedforward capacitor across the upper feedback resistor R1 is required to provide sufficient overdrive for the error comparator. The lower the switching frequency of the converter, the larger the feedforward capacitor value required. A good starting point is to use a 10pF feedforward capacitor. As a first estimat ion, the required value for the feedforward capacitor at the operation point can also be calculated using the following formula: 1R20 fsπ2 1CFF Where: R1=Upper resistor of voltage divider fS=Switching frequency of the converter at the nominal loa d current (See previous section for calculating the switching frequency) CFF=Choose a value that comes closest to the result of the calculation The larger the feedforward capacitor, the worse the line regulation of the device. Therefore, when concern for line regulation is paramount, the selected feedforward capacitor should be as small as possible. Output Capacitor Selection The output capacitor limits the output ripple and maintains the output voltage during large load transitions. Ceramic capacitors wi th X5R or X7R tempera ture characteristics are highly recommended due to their small size, low ESR, and small temperature coefficients. For most applications, a 1μF ceramic capacitor is sufficient. For some applications a reduction in output voltage ripple can be achieved by increasing the output capacitor. Input Capacitor Selection For good input voltage filtering, low ESR ceramic capacitors are recommended. A 4.7µF ceramic input capacitor is sufficient for most of the applications. For better input voltag e filtering this value can be increased. Diode Selection Schottky diode is a good choice for UM1665 because of its lo w forward voltage drop and fast reverse recovery. Using Schottky diode can get better efficiency. The current rating of the diode should meet the peak current rating of the converter as it is calculated in the peak current control section. Use the maximum value for ILIM for this calculation.
http://www.union-ic.com Rev.05 Mar.2016 12/15 UM1665 Layout Considerations High switching frequencies and relatively large peak currents make the PCB layout a very important part of design. Good design minimizes excessive EMI on the feedback paths and voltage gradients in the ground plane, resulting in a stable and well -regulated output. Good layout for the UM1665 can be implemented by following a few simple design rules. 1. The input capacitor should be placed as close as possible to the input pin for good input voltage filtering. 2. The inductor and diode should be placed as close as possible to the switch pin to minimize the noise coupling into other circuits. 3. The feedback network should be routed away from the inductor. The feedback pin and feedback network should be shielded with a ground plane or trace to minimize noise coupling into this circuit. 4. Wide traces shou ld be used for connections in bold as shown in the figure below. A star ground connection or ground plane minimizes ground shifts and noise. EN GND FB SWVIN UM1665 VIN L1 CFF COUT CIN VOUTD1
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Package Information
UM1665S: SOT23-5 Outline Drawing b D E e A Top View Side View 1 3 c L θ End View DIMENSIONS Symbol MILLIMETERS INCHES Min Typ Max Min Typ Max b 0.30 - 0.50 0.012 - 0.020 D 2.82 - 3.10 0.111 - 0.122 e 0.95REF 0.037REF e1 1.90REF 0.075REF L 0.30 - 0.60 0.012 - 0.024 θ 0° - 8° 0° - 8° Land Pattern 0.56 0.95 0.95 2.35 1.20 NOTES: 1. Compound dimension: 2.92×1.60; 2. Unit: mm; 3. General tolerance ±0.0 5mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation MPHO
http://www.union-ic.com Rev.05 Mar.2016 14/15 UM1665 UM1665DA: TDFN6 3.0×3.0 Outline Drawing D2D E (Pin #1 ID) e L(6X) Z(4X) A Side View Bottom View 45º(0.35*0.35) Top View b(6X) DIMENSIONS Symbol MILLIMETERS INCHES Min Typ Max Min Typ Max A3 0.15TYP 0.006TYP e 0.95TYP 0.037TYP Z 0.35TYP 0.014TYP Land Pattern 0.95 0.20 0.56 2.35 3.00 1.58 3.00 0.65 3.40 NOTES: 1. Compound dimension: 3.00×3.00; 2. Unit: mm; 3. General tolerance ±0.05mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation 1665 XX
http://www.union-ic.com Rev.05 Mar.2016 15/15 UM1665 GREEN COMPLIANCE Union Semiconductor is committed to environmental excell ence in all aspects of its operations including meeting or exceeding regulatory requirements with respect to the use of hazardous substances. Numerous successful programs have been implemented to reduce the use of hazardous substances and/or emissions. All Union components are compliant with the RoHS directive, which helps to support customers in their compliance with environmental directives. For more green compliance information, please visit: http://www.union-ic.com/index.aspx?cat_code=RoHSDeclaration IMPORTANT NOTICE The information in this document has been carefully reviewed and is believed to be accurate. Nonetheless, this document is subject to change without notice. Unio n assumes no responsibility for any inaccuracies that may be contained in this document, and makes no commitment to update or to keep current the contained information, or to notify a person or organization of any update. Union reserves the right to make c hanges, at any time, in order to improve reliability, function or design and to attempt to supply the best product possible. Union Semiconductor, Inc Add: Unit 606, No.570 Shengxia Road, Shanghai 201210 Tel: 021-51093966 Fax: 021-51026018 Website: www.union-ic.com