LTC3872EDDB#TRPBF Linear Technology, LTC3872EDDB#TRPBF Datasheet
LTC3872EDDB#TRPBF
Specifications of LTC3872EDDB#TRPBF
Available stocks
Related parts for LTC3872EDDB#TRPBF
LTC3872EDDB#TRPBF Summary of contents
Page 1
... High switching frequency of 550kHz allows the use of a small inductor. The LTC3872 is available in an 8-lead low profile (1mm) ThinSOT DFN package. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and No R and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks SENSE are the property of their respective owners ...
Page 2
... LTC3872ETS8#TRPBF LTC3872ITS8#PBF LTC3872ITS8#TRPBF LTC3872HTS8#PBF LTC3872HTS8#TRPBF LTC3872EDDB#PBF LTC3872EDDB#TRPBF LTC3872IDDB#PBF LTC3872IDDB#TRPBF LTC3872HDDB#PBF LTC3872HDDB#TRPBF Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. ...
Page 3
T PARAMETER Input Voltage Range Input DC Supply Current Normal Operation Shutdown UVLO Undervoltage Lockout Threshold Shutdown Threshold (at RUN/SS) Regulated Feedback Voltage Feedback Voltage Line Regulation Feedback Voltage Load Regulation V ...
Page 4
LTC3872 Typical perForMance characTerisTics FB Voltage vs Temperature 1.25 1.24 1.23 1.22 1.21 1.20 1.19 1.18 –60 –40 – TEMPERATURE (°C) 3872 G01 Shutdown ...
Page 5
Typical perForMance characTerisTics Gate Drive Rise and Fall Time vs C LOAD 100 RISE TIME 60 FALL TIME 2000 4000 6000 8000 10000 C (pF) LOAD 3872 G07 Frequency vs ...
Page 6
LTC3872 pin FuncTions (TS8/DD8) IPRG (Pin 1/Pin 4): Current Sense Limit Select Pin. I (Pin 2/Pin 3): It serves as the error amplifier com- TH pensation point. Nominal voltage range for this pin is 0.7V to 1.9V. V (Pin 3/Pin ...
Page 7
Main Control Loop The LTC3872 constant frequency, current SENSE mode controller for DC/DC boost, SEPIC and flyback converter applications. The LTC3872 is distinguished from conventional current mode controllers because the current control loop can be ...
Page 8
LTC3872 applicaTions inForMaTion Output Voltage Programming The output voltage is set by a resistor divider according to the following formula: R2 = 1.2V • The external resistor divider is connected ...
Page 9
V IN(MIN • D MAX ∆I • where: I O(MAX) = χ • ∆I L 1– D MAX Remember that boost converters are not ...
Page 10
LTC3872 applicaTions inForMaTion to 30V or less, and the switch node can ring during the turn-off of the MOSFET due to layout parasitics. Check the switching waveforms of the MOSFET directly across the drain and source terminals using the actual ...
Page 11
Calculating Power MOSFET Switching and Conduction Losses and Junction Temperatures In order to calculate the junction temperature of the power MOSFET, the power dissipated by the device must be known. This power dissipation is a function of the ...
Page 12
LTC3872 applicaTions inForMaTion For a 1% contribution to the total ripple voltage, the ESR of the output capacitor can be determined using the fol- lowing equation: 0.01• ESR ≤ COUT I IN(PEAK) where: I χ O(MAX) ...
Page 13
In the case of tantalum critical that the capacitors have been surge tested for use in switching power supplies. An excellent choice is AVX TPS series of surface mount tantalum. ...
Page 14
LTC3872 applicaTions inForMaTion output current. Assuming an efficiency of 90%, this sense resistor power dissipation represents 1.3% of the overall input power. In other words, for this application, the use of V sensing would increase the efficiency by DS approximately ...
Page 15
And so the inductor value is: V 3.3V IN(MIN • MAX ∆I • f 1.3A • 550kHz L The component chosen is a 2.2µH inductor made by Sumida (part number CEP125-H 1ROMH). 3. Assuming ...
Page 16
LTC3872 Typical applicaTions High Efficiency 3.3V Input, 12V Output Boost Converter 2.2nF 23.2k 100pF 11.8k 1% AC-COUPLED STEP FROM 500mA TO 1.5A 16 4.7M 0.1µF I RUN/ IPRG 2.2µH LTC3872 GND SW V NGATE M1 PDS1040 ...
Page 17
Typical applicaTions High Efficiency 5V Input, 12V Output Boost Converter 4.7M 1nF 2.2nF 11k I RUN/ 100pF IPRG LTC3872 GND SW V NGATE FB 11.8k 1% 107k TAIYO YUDEN TMK325BJ226MM OUT1 L1: TOKO D124C ...
Page 18
LTC3872 Typical applicaTions 63.4k 2.2nF 12.1k 1% Soft-Start RUN/SS 5V/DIV I L 5A/DIV V OUT 20V/DIV 40ms/DIV 18 High Efficiency 5V Input, 48V Output Boost Converter 1M 0.33µF I RUN/ IPRG L1 10µH LTC3872 ...
Page 19
DescripTion package DescripTion 0.61 ±0.05 (2 SIDES) 0.70 ±0.05 2.55 ±0.05 1.15 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.20 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC ...
Page 20
LTC3872 package DescripTion 0.40 MAX 3.85 MAX 2.62 REF RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.20 BSC DATUM ‘A’ 0.30 – 0.50 REF NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF ...
Page 21
... Added I-Grade and H-Grade parts. Changes reflected throughout the data sheet. Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
Page 22
... Current Mode Control, 2.5V ≤ V SENSE Step-Up or Step Down, 600kHz, SSOP-16, SSOP-28 Optimized for Driving 6V MOSFETs ThinSOT www.linear.com ● 3. 10µF V OUT 5V 2A ×2 3872 TA02 16V, Miniature Design IN ≤ ≤ 36V IN LT 0311 REV B • PRINTED IN USA LINEAR TECHNOLOGY CORPORA TION 2007 3872fb ...