LTC3608 LINER [Linear Technology], LTC3608 Datasheet
LTC3608
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LTC3608 Summary of contents
Page 1
... Soft-start capability for sup- ply sequencing is accomplished using an external timing capacitor. The regulator current limit is user programmable. A power good output voltage monitor indicates when the output is in regulation. The LTC3608 is available in a compact 7mm × 8mm QFN package 18V 10μ ...
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... 0.3V to –0. SGND 10 BOOST 11 RUN/ SGND 14 PART MARKING* PACKAGE DESCRIPTION LTC3608WKG 52-Lead (7mm × 8mm) Plastic QFN LTC3608WKG 52-Lead (7mm × 8mm) Plastic QFN http://www.linear.com/leadfree/ http://www.linear.com/tapeandreel/ TOP VIEW ...
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... I = 0mA to 20mA EXTVCC 20mA, V Rising CC EXTVCC I = 20mA EXTVCC V Rising FB V Falling FB V Returning 5mA PGOOD LTC3608 MIN TYP MAX UNITS 900 2000 μ μA 0.594 0.600 0.606 V 0.590 0.600 0.610 V 0.002 %/V –0.05 –0.3 % –5 ± ...
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... LOAD CURRENT (A) 3608 G04 4 Note 3: The LTC3608 is tested in a feedback loop that adjusts V achieve a specifi ed error amplifi er output voltage (I 85°C is not tested in production. This specifi cation is assured by design, characterization, and correlation to testing at 125°C. and power Note 4: The LTC3608E is guaranteed to meet performance specifi cations A from 0° ...
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... V 1000 100 10 3 CURRENT (μA) ON Maximum Valley Current Limit vs V Voltage RNG 125 0.5 0.6 0.7 0.8 0.9 V VOLTAGE (V) RNG LTC3608 I Voltage vs Load Current TH 2.5 2.0 1.5 CONTINUOUS MODE 1.0 DISCONTINUOUS MODE 0 LOAD CURRENT (A) 3608 G08 On-Time vs V Voltage ON 1000 I = 30μ VON 800 ...
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... LTC3608 TYPICAL PERFORMANCE CHARACTERISTICS Maximum Valley Current Limit vs Temperature –50 – 100 TEMPERATURE (°C) 3608 G16 Feedback Reference Voltage vs Temperature 0.62 0.61 0.60 0.59 0.58 –50 – TEMPERATURE (°C) Input and Shutdown Currents vs Input Voltage 1400 EXTV 1200 1000 800 SHUTDOWN ...
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... G25 Undervoltage Lockout Threshold vs Temperature 4.0 3.5 3.0 2.5 2 100 125 –50 –25 3608 G27 LTC3608 Switch Resistance 100 125 TEMPERATURE (°C) 3608 G24 PULL-DOWN CURRENT PULL-UP CURRENT 100 125 TEMPERATURE (°C) 3608 G26 ...
Page 8
... LTC3608 PIN FUNCTIONS PV (Pins 48, 49, 50, 51, 52, 53): IN Main Input Supply. Decouple this pin to power PGND with the input capacitance (Pins 8, 33, 41, 42, 43, 44, 45, 46, 47, 55): Switch Node Connection to the Inductor. The (–) terminal of the bootstrap capacitor C also connects here ...
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... EXTV 4.7V + – 1μA 0.6V – FCNT ON SWITCH I REV LOGIC SHDN OV 1V RUN SS SHDN – + 0.4V 12 RUN/SS LTC3608 0.6V 7, 48, 49, 50, REF 51, 52 REG INTV CC 31, 32 BOOST 33, 41, 42, 43, 44, 45, 46, 47 OUT ...
Page 10
... LTC3608 OPERATION Main Control Loop The LTC3608 is a high effi ciency monolithic synchronous, step-down DC/DC converter utilizing a constant on-time, current mode architecture. It operates from an input volt- age range 18V (20V maximum) and provides a regulated output voltage output current. The internal synchronous power switch increases effi ...
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... APPLICATIONS INFORMATION The basic LTC3608 application circuit is shown on the front page of this data sheet. External component selection is primarily determined by the maximum load current. The LTC3608 uses the on-resistance of the synchronous power MOSFET for determining the inductor current. The desired amount of ripple current and operating frequency also determines the inductor value ...
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... ON ON Minimum Off-time and Dropout Operation The minimum off-time t time that the LTC3608 is capable of turning on the bottom MOSFET, tripping the current comparator and turning the MOSFET back off. This time is generally about 320ns. The minimum off-time limit imposes a maximum duty = 5V ...
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... The selection of C ESR required to minimize voltage ripple and load step transients. The output ripple ΔV bounded by: V OUT LTC3608 . The largest ripple current OUT(MAX guarantee that ripple current OUT ...
Page 14
... V forced until V V OUT2(MIN) Fault Conditions: Current Limit and Foldback The LTC3608 has a current mode controller which inher- ) ently limits the cycle-by-cycle inductor current not only B in steady state operation but also in transient. To further limit current in the event of a short circuit to ground, the LTC3608 includes foldback current limiting ...
Page 15
... Soft-Start and Latchoff with the RUN/SS Pin The RUN/SS pin provides a means to shut down the CC LTC3608 as well as a timer for soft-start and overcurrent latchoff. Pulling the RUN/SS pin below 0.8V puts the CC LTC3608 into a low quiescent current shutdown (I CC 30μ ...
Page 16
... Although all dissipative elements in the circuit produce losses, four main sources has reached account for most of the losses in LTC3608 circuits losses. These arise from the resistance of the internal resistance of the MOSFETs, inductor and PC board traces and cause the effi ...
Page 17
... LTC3608. • Place C = OUT the LTC3608. It may help to have some components on the bottom side of the board. • Keep small-signal components close to the LTC3608. ≈ 187k • Ground connections (including LTC3608 SGND and PGND) should be made through immediate vias to the ground plane ...
Page 18
... These items are also illustrated in Figure 7. 18 INTV 0.47μF VCC 4.7μF 25V 6. LTC3608 PGOOD ...
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... LTC3608 Figure 7. LTC3608 Layout Diagram LTC3608 26 SGND SGND 19 FCB RNG 16 ...
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... LOAD STEP 1A- 3. 1.5V OUT FCB = 0V 20 3.6V Input to 1.5V/8A at 750kHz INTV 0.47μF C VCC 25V 4.7μF 6. LTC3608 PGOOD 0.22μF INTV 0.1μF 3608 TA02a IN2 ...
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... LTC3608 PGOOD 0.22μF INTV CMDSH 0.1μF 3608 TA03a LTC3608 R F1 1Ω V IN2 EXTV CC C4 0.01μF SGND 26 SGND 30k C1 30. (OPTIONAL) ...
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... LOAD STEP 1A- 12V 1.8V OUT FCB = 18V Input to 1.8V/8A All Ceramic 1MHz INTV 0.1μF C VCC 25V 4.7μF 6. LTC3608 PGOOD 0.22μF INTV CMDSH 0.1μF ...
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... DIMENSION b SHOULD NOT BE MEASURED IN THAT RADIUS AREA. 8.50 ± 0.05 8 COPLANARITY APPLIES TO THE TERMINALS AND ALL OTHER SURFACE METALLIZATION 9 DRAWING SHOWN ARE FOR ILLUSTRATION ONLY SYMBOL TOLERANCE PACKAGE aaa OUTLINE bbb ccc 1.35 ± 0.10 LTC3608 2.625 REF 2.90 REF 0.50 BSC 2.025 3.40 REF ± 0.10 2.925 ± 0. 4.275 ± 0. ...
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... McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● 14V to 18V Input to 12V/5A at 500kHz C VCC INTV CC 4.7μF , 6.3V PGND LTC3608 ...