UM1660 UNIONSEMI | Alldatasheet
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Technical content
Features
LCD Bias Supply White LED Supply for LCD Backlights Digital Still Camera 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 36µ A Typical No Load Quiescent Current 1µ A Maximum Shutdown Current Internal Soft-Start Available in Tiny SOT23 -5 and DFN6 2.0× 2.0 Packages Pin Configurations Top View (Top View) SW GND FB EN VIN1 3 4 1 2 3 MPHO M: Month Code UM1660S SOT23-5 (Top View) 1VIN GND EN FB NC SW 3 4 AAG M Marking Pin1 M: Month Code UM1660DA DFN6 2.0× 2.0
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Ordering Information
Part Number Packaging Type Marking Code Shipping Qty UM1660S SOT23-5 PHO 3000pcs/7Inch Tape & Reel UM1660DA DFN6 2.0× 2.0 AAG 3000pcs/7Inch Tape & Reel Pin Description Pin Number Symbol Function UM1660S UM1660DA 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 pi n 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 1µ A. 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 DFN6 2.0× 2.0 0.7 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 the 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. UM1660 function block diagram
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Electrical Characteristics
(VIN= 2.4 V, EN = VIN, CIN=4.7μF, COUT=1μF, L=10μH, 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 350 400 450 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 Feb.2014 5/15 UM1660 Operation The UM1660 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 6µ s (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 diode 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 volta ge again. Using this PFM peak current control scheme the converter operates in discontinuous 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 reaches the typical dc current limit (I LIM) of 400mA. There is approximately a 100ns delay from the time the current limit is reached and when the internal logic actually turns off t he switch. During this 100ns delay, the peak inductor current will increase. This increase demands a larger saturation current rating for the inductor. This saturation current can be approximated by the following equation: nsL VinII LIMtyppeak 100)( The higher the input voltage and the lower the inductor value, the greater the 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 d uring start up and may result in an unwanted or early system shut down. The UM1660 limits this inrush current by increasing the current limit in two steps from I LIM/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 current to 1µ A (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 volta ge during shutdown. The enable pin needs to be terminated and should not be left floating. Using a small external transistor disconnects the input from the output during shutdown as shown in the figure below.
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50 Hz to 10kHz
(Optional) 82Ω VIN=2.7- 6V COUT 1µF Figure 4. White LED Supply with Adjustable Brightness Control Using a PWM Signal on the Enable Pin We also can adjust the white LED brightness using an analog signal on the feedback pin (see figure 5 below). Add a DC voltage to the FB pin, and adjust the LED current by change the DC voltage, which control the brightness. The LED current is calculated as: 121 RR RVRRVI S ADJFB RS EN GND FB SWVIN UM1660 10µH CIN 4.7µF Rs 30V (Optional) Cout* 100nF *A smaller output capacitor value for Cout causes a larger LED ripple VIN=2.7- 6V ADJ V VFB Figure 5. White LED Supply with Adjustable Brightness Control Using an Analog Signal on the Feedback Pin
http://www.union-ic.com Rev.05 Feb.2014 8/15 UM1660 Typical Operating Characteristics （CIN=4.7μF, COUT=1μF, L=10μH, TA=25℃, 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 VO=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 VO=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, VO=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℃
http://www.union-ic.com Rev.05 Feb.2014 9/15 UM1660 Typical Operating Characteristics (Continued) （CIN=4.7μF, COUT=1μF, L=10μH, TA=25℃, 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 VO 100mV/div VO=18V, IO=10mA IO=1mA to 10mA VO 100mV/div VIN=3.3V, VO=18V VOUT 5V/div EN 2V/div VIN=3.6V, VO=18V, IO=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, IO=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 Feb.2014 10/15 UM1660 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 33µH 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: VoutLIp VinVoutVinfs )(min max Where: IP = Peak current as described in the previous peak current control section L = Selected inductor value Vinmin = The highest switching frequency occurs at the minimum input voltage 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: LIp VdVinVoutIIfs load load )(2)( 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: )(2 max max VinVout fsLIpIload 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 Feb.2014 11/15 UM1660 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 important 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: 11(233.1 R RVVout For battery powered applications a high i mpedance 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 R 1 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 estim ation, the required value for the feedforward capacitor at the operation point can also be calculated using the following formula: 1202 RfsCFF Where: R1 = Upper resistor of voltage divider fS = Switching frequency of the converter at the nomin al load 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 capaci tors with 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 4.7µ F ceramic input capacitor is sufficient for most of the applications. For better input voltage filtering this value can be increased. Diode Selection Schottky diode is a good choice for UM1660 because of its low 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 Feb.2014 12/15 UM1660 Layout Considerations High switching frequencies and relatively large peak currents make t he 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 UM1660 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 should 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 UM1660 VIN L1 CFF COUTCIN VOUTD1
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Package Information
UM1660S: SOT23-5 Outline Drawing 1 2 3 b D e E Top View θ L End View A1 A2 A Side View 0.2 c DIMENSIONS Symbol MILLIMETERS INCHES Min Max Min Max A 1.050 1.250 0.041 0.049 A1 0.000 0.100 0.000 0.004 A2 1.050 1.150 0.041 0.045 b 0.300 0.500 0.012 0.020 c 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 1.500 1.700 0.059 0.067 E1 2.650 2.950 0.104 0.116 e 0.950REF 0.037REF e1 1.800 2.000 0.071 0.079 L 0.300 0.600 0.012 0.024 θ 0° 8° 0° 8° Land Pattern 0.70 0.90 2.40 0.95 0.95 NOTES: 1. Compound dimension: 2.92× 1.60; 2. Unit: mm; 3. General tolerance ± 0.05mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation MPHO
http://www.union-ic.com Rev.05 Feb.2014 14/15 UM1660 UM1660DA: DFN6 2.0× 2.0 Outline Drawing D2/2 D E2/2 E e b L R 0.100 Bottom View A A3Side View DIMENSIONS Symbol MILLIMETERS Min Typ Max A 0.57 0.60 0.63 A1 0 0.03 0.05 A3 0.15TYP b 0.20 0.25 0.30 D 1.95 2.00 2.075 E 1.95 2.00 2.075 D2 1.45 1.55 1.65 E2 0.76 0.86 0.96 e 0.65TYP L 0.30 0.35 0.40 Land Pattern 1.00 1.20 2.50 0.65 0.65 0.25 NOTES: 1. Compound dimension: 2.00×2.00; 2. Unit: mm; 3. General tolerance ± 0.05mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation AAG M
http://www.union-ic.com Rev.05 Feb.2014 15/15 UM1660 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. Union 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 changes, at any time, in order to improve reliability, function or design and to attempt to supply the best product possible. Union Semiconductor, Inc Add: 2F, No. 3, Lane 647 Songtao Road, Shanghai 201203 Tel: 021-51093966 Fax: 021-51026018 Website: www.union-ic.com