sc173a Semtech Corporation, sc173a Datasheet
sc173a
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sc173a Summary of contents
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... Enable December 16 , 2010 3A EcoSpeed Regulator with Automatic Power Save Description The SC173A is an integrated, synchronous 3A EcoSpeed step-down regulator, which incorporates TM Semtech’s advanced, patented adaptive on-time archi- tecture to achieve best-in-class performance in dynamic point-of-load applications. The input voltage range ...
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... Date Code (Example: 0952) xxxx = Semtech Lot Number (Example: 3901) © 2010 Semtech Corporation Ordering Information Device SC173AMLTRT SC173AEVB VDD Notes: AGND 1) Available in tape and reel packaging only. A reel contains 3000 devices. TON 2) Available in lead-free packaging only. WEEE compliant and Halogen EN free ...
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... J Symbol Conditions Rising UVLO =0A (1) OUT See R Calculation TON FB=VDD Continuous Conduction V =5V, V =3V, R =200kΩ IN OUT TON SC173A ………… 40°C/W (1) Min Typ Max Units 3 5.5 V 2.75 2.85 2.98 V 100 200 μA 500 0.7425 ...
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... Protection Threshold OV, UV Fault Noise Immunity Delay Over-Temperature Shutdown Enable Output Enabled Output Disabled EN Input Bias Current Enable Pin Floating Voltage © 2010 Semtech Corporation < 125°C J Symbol Conditions Power Good Signal Threshold High Power Good Signal Threshold Low VDD=3V VDD=5V ...
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... Non-overlap time (1) Note: (1) Typical value from EVB, not ATE tested. © 2010 Semtech Corporation < 125°C J Symbol Conditions Valley Current Limit, VDD=5V Valley Current Limit, VDD=3V VIN=5.5V, LX=0V, High Side High Side Low Side SC173A Min Typ Max Units 25 45 Ω µ ...
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... AGND Analog Ground. Input power for internal control circuit. Needs at least 2.2mF decoupling capacitor from this pin to 10 VDD AGND. Thermal pad for heatsinking purposes. Connect to ground plane using multiple vias. Not con- PAD nected internally. © 2010 Semtech Corporation SC173A . 6 ...
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... Block Diagram 10 VDD AGND Reference 9 Soft Start TON © 2010 Semtech Corporation PGOOD Control Gate Drive Control On-Time Generator Zero-Cross Valley Current Limit 1 VDD BST VIN VDD PGND ...
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... DS84LC-B1015AS-2R2N OUT 1.216 C = OUT R = 54.9kOhm TON 1.214 1.212 1.210 0.00 0.60 1.20 1.80 2.40 Output Current (A) Output Voltage vs Output Current Vo=1.212V 54.9kOhm TON 1.216 L : DS84LC-B1015AS-2R2N OUT C : OUT 1.214 1.211 1.209 1.206 Black: Vin=5V Red: Vin=4V Blue: Vin=3.5V 1.204 1.201 0.00 0.75 1.50 2.25 Output Current (A) SC173A 3.00 3.00 3.00 8 ...
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... Channel 1: 500mV/Div, Channel 4: 1A/Div, Time: 1ms/Div 85 110 135 Load Transient Test ( L =1.0 H,C OUT 2:5V/Div,Channel 4:2A/Div,Time:20 s/Div) 75 100 125 Load Transient Test ( L =1 OUT 2:5V/Div,Channel 4:2A/Div, Time:20 s/Div) 75 100 125 SC173A V =5V, V =1.2V, I =3A, IN OUT OUT V =5V, V =1.2V 3A, IN OUT OUT =2x22 F,Channel 1: 50mV/Div, Channel OUT V =5V, V =1.2V, I ...
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... Low Side Switch On-State Resistance vs Temperature Blue: VDD=3.0V 34 Black: VDD=5.0V 30 -40 - Temperature (°C) © 2010 Semtech Corporation 85 110 135 SC173A High Side Switch On-State Resistance vs Temperature Blue: VDD=3.0V 44 Black: VDD=5.0V 40 -40 - 110 Temperature (°C) 135 10 ...
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... Applications Information SC173A Synchronous Buck Converter The SC173A is a step down synchronous buck dc-dc regu- lator. The SC173A is capable of 3A operation at very high efficiency in a tiny 3x3-10 pin package. The programma- ble operating frequency range of 200kHz – 1MHz (con- tinuous conduction mode) enables the user to optimize the solution for minimum board space and optimum ef- ficiency ...
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... IN R TON Figure 2 — On-Time Generation The SC173A uses an external resistor to set the on-time which indirectly sets the frequency. The on-time can be programmed to provide operating frequency from 200kHz to 1MHz using a resistor between the TON pin and ground. The resistor value is selected by the fol- lowing equation ...
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... FETs until VDD rises above 2.9V. An internal Power-On Reset (POR) occurs when VDD exceeds 2.9V, which resets the fault latch and soft start counter to begin the soft start cycle. The SC173A then begins a soft start cycle. The PWM will shut off if VDD falls below 2.7V. ...
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... The desired switching frequency is 800kHz which results from using components selected for optimum size and cost . A resistor ( used to program the on-time (indirectly TON © 2010 Semtech Corporation setting the frequency) using the following equation. Calculating R R =50kW, we use R TON ) is the highest speci- ...
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... OUT RIPPLE = MAX I 0.51A RIPPLEMAX = 78.3 mΩ MAX 1 L × × I OUT RIPPLEMAX 2 COUT = MIN PEAK OUT of 1.050V (50mV rise upon PEAK × (3A + × 0.511A MIN (1.05V (1.0V) 2 /dt. Peak inductor current is LOAD SC173A 207 ...
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... This ripple voltage is the sum of the two voltages. One is the ripple generated by the ESR, the other is the ripple due to capacitive charging capacitor will couple TOP C TOP To FB pin V R1 OUT R2 Figure 6 — Capacitor Coupling to FB Pin SC173A 16 ...
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... OUT for added stability. The on-time pulse from the SC173A in the design ex- SW ample is calculated to give a pseudo-fixed frequency of 800kHz. Some frequency variation with line and load is expected. This variation changes the output ripple volt- age. Because adaptive on-time converters regulate to the valley of the output ripple, ½ ...
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... LX pin voltage is measured on the voltage por- tion which is either over 6.0V for positive voltage spike or under -1V for negative voltage spike. The LX voltage is measured from the LX pin to the PGND pin by using a probing loop which is as short as possible to minimize or eliminate the switching noise pick up. IN combination, to offset SC173A 18 ...
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... C11, with a value between 1nF and 10nF, is the high frequency filter- ing capacitor recommended to put C1 and C11 as close as possible to the SC173A to get the best decou- pling performance, with C11 closest. C1, with a value of 10uF, should be placed no more than 3mm away from the VIN pin ...
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... R6 in series with C9 is connected to the LX pin (through the via) to the power ground the coupling capacitor which injects the ramp signal generated the FB pin of the SC173A the pull up resistor for the PGOOD pin. © 2010 Semtech Corporation SC173A ...
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... VIN © 2010 Semtech Corporation V IN C11 C1 PGND AGND PGND AGND Top Layer C6 R1 C10 AGND R2 EN/PSV Inner Layer 1 21 ...
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... VIN PGND © 2010 Semtech Corporation PGND 5 6 AGND AGND Inner Layer 2 Bottom Layer 22 ...
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... R5 C10 4.32k C18 68pF C19 R2 10n 15k SC173A R1 5.11Ohm 0.1uF/6.3V SC173A 10uF/6.3V VDD BST C5 VIN AGND R3 LX TON 54.9k PGND EN/PSV PGOOD FB R1 5.11Ohm 0.1uF/6.3V SC173A 10uF/6.3V VDD BST C5 AGND VIN R3 LX TON 80.6k PGND EN/PSV PGOOD FB C501 Enable FB C501 Enable FB 23 ...
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... Outline Drawing - MLPD-10 3x3 A PIN 1 INDICATOR (LASER MARK) aaa C 1 LxN E/2 N D/2 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS. © 2010 Semtech Corporation D B DIM aaa bbb A SEATING PLANE ...
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... FUNCTIONAL PERFORMANCE OF THE DEVICE. © 2010 Semtech Corporation K DIM C K DIMENSIONS G DIM INCHES H G (.112 .079 .059 .089 X P .020 .012 Z .033 .146 P SC173A DIMENSIONS INCHES MILLIMETERS (.114) (2.90) .083 2.10 MILLIMETERS .055 1.40 (2.85) .087 2.20 2.00 .020 1.50 0.50 2.25 .012 0.30 0.50 .031 0.80 0.30 .146 3.70 0.85 3.70 25 ...
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... Contact Information © 2010 Semtech Corporation Semtech Corporation Power Mangement Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com SC173A 26 ...