LT3682 LINER [Linear Technology], LT3682 Datasheet
LT3682
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LT3682 Summary of contents
Page 1
... Schottky catch diode to protect the LT3682 against short-circuit conditions. Frequency foldback and thermal shutdown provide additional protection. The LT3682 is available in a 12-Pin 3mm × 3mm DFN with exposed pad for low thermal resistance. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation ...
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... BD and PG Voltage ..…….………………..……….. 30V Operating Junction Temperature Range (Notes 3 and 6) LT3682E ……………….………….. . −40°C to 125°C LT3682I ……………………………. −40°C to 125°C Storage Temperature Range … ...
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... RUN/SS pins is 60V for IN nonrepetitive 1 second transients, and 36V for continuous operation. Note 3: The LT3682E is guaranteed to meet performance specifi cations from 0°C to 125°C junction temperature. Specifi cations over the −40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3682I is guaranteed over the full − ...
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... LT3682 TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency (V = 5V, SYNC = 0V) OUT 12V 34V 24V 10μ 800kHz 10 10 0.1 1 100 1000 LOAD CURRENT (mA) 3682 G01 No Load Supply Current 120 V = 3.3V OUT 100 INPUT VOLTAGE(V) ...
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... TEMPERATURE(°C) Minimum Switch On-Time 120 100 900 TEMPERATURE (°C) LT3682 T = 25°C, unless otherwise noted. A Switch Voltage Drop 700 600 500 400 300 200 100 0 100 125 0 0.5 0.75 0.25 SWITCH CURRENT (A) 3682 G11 Switching Frequency 1 ...
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... LT3682 TYPICAL PERFORMANCE CHARACTERISTICS RUN/SS Pin Current RUN/SS PIN VOLTAGE (V) 3682 G19 Minimum Input Voltage 5 4 3.3V 2.5 OUT L = 10μ 800kHz 100 LOAD CURRENT (mA) 3682 G22 Maximum V for Full Frequency 85˚C ...
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... G28 V SW 5V/DIV 0.5A/DIV V OUT 20mV/DIV 3682 G30 1μs/DIV LT3682 T = 25°C, unless otherwise noted. A Switching Waveforms; Burst Mode I L 3682 G29 5μs/DIV V = 12V; FRONT PAGE APPLICATION 5mA LOAD Switching Waveforms; Full Frequency Continuous Operation ...
Page 8
... SW (Pin 8): The SW pin is the output of the internal power switch. Connect this pin to the inductor, catch diode and boost capacitor. RUN/SS (Pin 9): The RUN/SS pin is used to put the LT3682 in shutdown mode. Tie to ground to shut down the LT3682. Tie to 2.5V or more for normal operation. RUN/SS also provides a soft-start function ...
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... 0.720V – GND – OVLO + SLOPE COMP OUT OSCILLATOR 250kHz-2.2MHz OUTB SYNC DISABLE BURST MODE DETECT ERROR AMP VC CLAMP + – LT3682 THERMAL BD SHUTDOWN 5 BOOST – PGND 13 V OUT ...
Page 10
... FB pin is at 90% of its regulated value. The PG output is an open-collector transistor that is off when the output is in regulation, allowing an external resistor to pull the PG pin high. Power good is valid when the LT3682 is enabled and V The LT3682 has an overvoltage protection feature which disables switching action when the V typical (36V minimum) during transients ...
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... V Reference designators refer to the Block Diagram. 1% resistors are recommended to maintain output voltage accuracy. Setting the Switching Frequency The LT3682 uses a constant frequency PWM architecture that can be programmed to switch from 250kHz to 2.2MHz by using a resistor tied from the R T showing the necessary R value for a desired switching T frequency is in Figure 1 ...
Page 12
... Special attention must be paid when the output is in start- up, short-circuit, or other overload conditions. In these cases, the LT3682 tries to bring the output in regulation by driving lots of current into the output load. During these events, the inductor peak current might easily reach and ...
Page 13
... SW is the duty cycle and L is the value of the inductor. To maintain output regulation, the inductor peak current must be less than the LT3682’s switch current limit I If SYNC pin is grounded I cycles and decreases to 1. 90%. If SYNC pin is tied to 0.8V or more tied to a clock source for ...
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... Shielded with the inductor, it fi lters the square wave generated by the Open LT3682 to produce the DC output. In this role it determines the output ripple, and low impedance at the switching frequency is important. The second function is to store energy in order to satisfy transient loads and stabilize the LT3682’ ...
Page 15
... LT3682 due to their piezoelectric nature. When in Burst Mode operation, the LT3682’s switching frequency depends on the load current, and at very light loads the LT3682 can excite the ceramic capacitor at audio frequencies, generating audible noise. Since the LT3682 operates at a lower current limit during Burst Mode operation, the noise is typically very quiet ...
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... The LT3682 uses current mode control to regulate the output. This simplifi es loop compensation. In particular, the LT3682 does not require the ESR of the output capacitor for stability, so you are free to use ceramic capacitors to achieve low output ripple and small circuit size. Frequency ...
Page 17
... OUT Load Current is Stepped from 300mA to 650mA. Low Ripple Burst Mode and Pulse-Skip Mode The LT3682 is capable of operating in either Low Ripple Burst Mode or Pulse-Skip Mode which are selected using the SYNC pin. See the Synchronization section for more information. To enhance effi ciency at light loads, the LT3682 can be ...
Page 18
... For proper startup, the minimum input voltage is also limited by the boost circuit. If the input voltage is ramped slowly, or the LT3682 is turned on with its RUN/SS pin when the output V IN (5a) For V ...
Page 19
... higher load currents, the inductor current is OUT continuous and the duty cycle is limited by the maximum duty cycle of the LT3682, requiring a higher input voltage to maintain regulation. Soft-Start The RUN/SS pin can be used to soft-start the LT3682, reducing the maximum input current during start-up. The ...
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... Figure 8). There is another situation to consider in systems where the output will be held high when the input to the LT3682 is absent. This may occur in battery charging applications or in battery backup systems where a battery or some other supply is diode OR-ed with the LT3682’ ...
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... Figure 10. A Good PCB Layout Ensures Proper, Low EMI Operation , FB, and R . Finally, T the LT3682 possible to dissipate enough heat to raise the junction temperature beyond the absolute maximum of 125°C. When operating at high ambient temperatures, the maximum load current should be derated as the ambient temperature approaches these maximums ...
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... OFF RUN/SS BOOST V SW LT3682 14k PG SYNC FB 40.2k GND PGND 470pF f = 800kHz 1.8V Step-Down Converter OFF RUN/SS BOOST LT3682 17.4k PG SYNC FB 71.5k GND PGND 330pF f = 500kHz V OUT 5V 0.9A, V 6.9V IN 1A, V 12V IN L 0.22μF 10μH D1 B150 536k 102k 10μF 3682 TA02 ...
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... DD Package 12-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1725 Rev A) 0.70 0.05 2.38 0.05 PACKAGE OUTLINE 0.45 BSC 2.25 REF R = 0.115 TYP 7 3.00 0.10 1.65 0.10 (4 SIDES) 6 0.75 0.05 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD LT3682 0.40 0.10 12 2.38 0.10 PIN 1 NOTCH R = 0.20 OR 0.25 45 CHAMFER 1 0.23 0.05 0.45 BSC 2.25 REF (DD12) DFN 0106 REV A 3682f 23 ...
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... ThinSOT is a trademark of Linear Technology Corporation. 24 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● 5V, 2MHz Step-Down Converter OFF RUN/SS BOOST LT3682 13.3k PG SYNC FB 9.76k GND PGND 680pF f = 2MHz COMMENTS V = 5.5V to 60V TSSOP16E Package ...