ltc3440 Linear Technology Corporation, ltc3440 Datasheet
ltc3440
Available stocks
Related parts for ltc3440
ltc3440 Summary of contents
Page 1
... MODE/SYNC pin has either a clock or is driven low, then fixed frequency switching is enabled. Other features include a 1μA shutdown, soft-start con- trol, thermal shutdown and current limit. The LTC3440 is available in the 10-pin thermally enhanced MSOP and (3mm × 3mm) DFN packages. ...
Page 2
... Buck (% Switch A On 5.5V MODE/SYNC ORDER PART TOP VIEW NUMBER SHDN/SS LTC3440EMS OUT MS PACKAGE 10-LEAD PLASTIC MSOP PART MARKING T = 125°C, JMAX = 130° LAYER BOARD LTNP = 100° LAYER BOARD θ ...
Page 3
... SHDN/SS Threshold SHDN/SS Input Current Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: The LTC3440E is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the – 40°C to 85°C operating W U TYPICAL PERFOR A CE CHARACTERISTICS Li-Ion to 3 ...
Page 4
... LTC3440 W U TYPICAL PERFOR A CE CHARACTERISTICS Switch Pins in Buck Mode SW1 2V/DIV SW2 2V/DIV 250ns/DIV 3440 G07 3.3V OUT I = 250mA OUT Active Quiescent Current 550 3.6V IN OUT 500 450 400 –55 – 125 TEMPERATURE (°C) 3440 G10 Output Frequency 1 ...
Page 5
... TEMPERATURE (°C) 3440 G17 Minimum Start Voltage 2.40 2.35 2.30 2.25 –55 – 125 TEMPERATURE (°C) 3440 G20 LTC3440 PMOS R DS(ON) 0. 3.6V IN OUT SWITCHES A AND D 0.25 0.20 0.15 0.10 –55 – 125 TEMPERATURE (°C) 3440 G18 Current Limit 3000 ...
Page 6
... LTC3440 CTIO S R (Pin 1): Timing Resistor to Program the Oscillator T Frequency. The programming frequency range is 300kHz to 2MHz • OSC R T MODE/SYNC (Pin 2): MODE/SYNC = External CLK : Syn- chronization of the internal oscillator. A clock frequency of twice the desired switching frequency and with a pulse width between 100ns and 2μ ...
Page 7
... SW C – + CONDUCTION I REVERSE SENSE AMP CURRENT LIMIT – + PWM LOGIC PWM AND COMPARATORS OUTPUT PHASING – + Burst Mode OPERATION CONTROL SHUTDOWN 5μs DELAY 5 GND LTC3440 V OUT 6 ERROR AMP + 1.22V FB – 9 CLAMP SHDN/ OUT 2. 3440 BD ...
Page 8
... Figure 1 shows a simplified diagram of how the four internal switches are connected to the inductor, V and GND. Figure 2 shows the regions of operation for the LTC3440 as a function of the internal control voltage, V pin to ground where: The V voltage is a level shifted voltage from the output of ...
Page 9
... Figures 3 and 4. During Burst Mode operation, the . SW control loop is nonlinear and cannot utilize the control LTC3440 , where the four switch region begins IN V OUT V 1 150 – ...
Page 10
... LTC3440 U OPERATIO voltage from the error amp to determine the control mode, therefore full-time 4-switch mode is required to maintain the Buck/Boost function. The efficiency below 1mA becomes dominated primarily by the quiescent current and not the peak efficiency. The equation is given by: η ( bm) • I LOAD ≈ ...
Page 11
... ENABLE – Figure 5. Soft-Start Circuitry W U Inductor Selection The high frequency operation of the LTC3440 allows the use of small surface mount inductors. The inductor cur rent ripple is typically set to 20% to 40% of the maximum 9 inductor current. For a given ripple the inductance terms ...
Page 12
... LTC3440 U U APPLICATIO S I FOR ATIO Ripple = allowable inductor current ripple (e.g., 0 minimum input voltage, V IN(MIN maximum input voltage, V IN(MAX output voltage, V OUT I = maximum output load current OUT(MAX) For high efficiency, choose an inductor with a high fre- quency core material, such as ferrite, to reduce core loses. ...
Page 13
... F = switching frequency W U Closing the Feedback Loop is required for output The LTC3440 incorporates voltage mode PWM control. The control to output gain varies with operation region (Buck, Boost, Buck-Boost), but is usually no greater than 15. The output filter exhibits a double pole response is given by: ...
Page 14
... Figure 8. Error Amplifier with Type III Compensation Short-Circuit Improvements The LTC3440 is current limited to 2.7A peak to protect the IC from damage. At input voltages above 4.5V a current limit condition may produce undesirable voltages to the IC due to the series inductance of the package, as well as the traces and external components. Following the recom- Hz mendations for output voltage > ...
Page 15
... 1.5MHz OSC 0 0 100 OUTPUT CURRENT (mA) 3440 TA03b LTC3440 INPUT_VOLTAGE C1 V1 10μF R1 0.5Ω Q1 VIN_PIN 2N3906 FB_PIN Figure 10. Simple Input Current Control Utilizing the Voltage Loop V OUT 3.3V 600mA C3 33pF R1 R5 340k 10k C2 22μF R2 200k ...
Page 16
... GND 1.5nF 200k f = 1MHz OSC C1: TAIYO YUDEN JMK212BJ106MG 3440 TA06a C2: TAIYO YUDEN JMK325BJ226MM D1: ON SEMICONDUCTOR MBRM120T3 L1: SUMIDA CDRH4D28-100 L1 4.7μ SW1 SW2 LTC3440 OUT 8 9 SHDN/ MODE/SYNC 4.7μ 15k R GND T 1 ...
Page 17
... MODE/SYNC 10μ GND T 10nF R T 60.4k + 2N3906 1/2 LT1490A – 1.22 • CURRENTLIMIT R5 • LTC3440 Efficiency of the WCDMA Power Amp Power Supply – 1.22V) 100 V = 3.4V OUT 100mA OUT 250mA OUT 600mA OUT 2.5 ...
Page 18
... LTC3440 PACKAGE DESCRIPTIO 3.50 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) 0.25 ± 0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699) 0.675 ±0.05 PIN 1 PACKAGE TOP MARK OUTLINE (SEE NOTE 6) 0.200 REF NOTE: 1 ...
Page 19
... TYP 0.53 ± 0.152 (.021 ± .006) 1.10 (.043) DETAIL “A” MAX SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP LTC3440 0.497 ± 0.076 (.0196 ± .003 REF 3.00 ± 0.102 (.118 ± .004) (NOTE 0.86 ( ...
Page 20
... LTC3440 U TYPICAL APPLICATIO Li-Ion to 3.3V at 600mA Buck-Boost Converter L1 10μH 3 SW1 SW2 LTC3440 V = 2. OUT 8 SHDN/ MODE/SYNC Li-Ion 10μ GND 60. Burst Mode OPERATION C1: TAIYO YUDEN JMK212BJ106MG 0 = FIXED FREQUENCY C2: TAIYO YUDEN JMK325BJ226MM L1: SUMIDA CDRH4D28-100 RELATED PARTS ...