Welcome to the training module on Introducing the Buck-Boost µModule Regulators .
Welcome to the training. This module will introduce µModule Buck-Boost Regulators from Linear Technology.
DC/DC buck (step-down) converters and boost (step-up) converters address a unidirectional voltage conversion by regulating a voltage less than or more than the input supply. The question of how to regulate a voltage accurately using bidirectional conversion, if the input supply varies above, below or equal to the output voltage, has been answered by the buck-boost DC/DC regulator. The buck-boost regulator performs three functions autonomously: 1) steps down Vin when Vout is less than Vin, 2) keeps output regulated when Vin equals Vout, and 3) steps up Vin when it is less than Vout. For example, consider a battery that when fully charged its voltage is 12V and when used and almost drained its voltage gradually decreases to 8V. If one wants a 10V regulation to power a DVD player from this battery, a buck-boost DC/DC regulator topology accomplishes this task by bucking the charged battery from 12V to 10V, and boosting the drained battery from 8V to 10V. When the battery is charged, its voltage rises to 12V again. Automotive, avionics, motor control, and marine power systems are examples of markets using a bust-boost regulator.
The Buck-Boost µModule Regulators have wide input capability voltages, ranging from 4.5V to 36V, to produce wide range output voltages ranging from 0.8V to 34V. This family can deliver output currents up to 10A, which can also be paralleled for higher output current. Efficiency values can reach up to 98%, with minimal power loss. A constant frequency current mode architecture allows a selectable fixed or phase-lockable frequency from 200kHz to 400kHz. Other features include ultra-fast transient response, pin compatibility, and current mode control to cover a broad range of applications, all packaged in a low profile surface mount measuring 15mm x 15mm x 2.8mm. Also included in each µmodule regulator is a current foldback and output overvoltage protection circuit. The following page provides specifics for each µModule regulator in the family.
The Buck-Boost DC/DC µModule family consists of three devices. The first µModule is the LTM4605, which has an input voltage range of 4.5V to 20V, with an output voltage range of 0.8V to 16V. Next in the family is the LTM4607, which features a higher input voltage range of 4.6V to 36V, and a higher output voltage range of 0.8V to 24V. Finally, the LTM4609, also features an input voltage range of 4.5V to 36V, but boasts a 0.8V to 34V output voltage range. All products in the family deliver exceptional efficiencies and minimal power loss. For a look at the µModule device applications, please view the next pages.
The Buck-Boost µModule family offers compact and simple solutions for a wide array of applications including Telecom, Servers, Networking, Industrial, Automotive, and High Power Battery-Operated Devices.
The non-isolated buck-boost DC/DC power supply has an integrated current mode buck-boost control, ultralow RDS(ON) FETs with fast switching speed and integrated Schottky diodes. With current mode control and internal feedback loop compensation, the buck-boost µ module has sufficient stability margins and good transient performance under a wide range of operating conditions and with a wide range of output capacitors. The frequency of the buck-boost µ module can be operated from 200kHz to 400kHz by setting the voltage on the PLLFLTR pin. Alternatively, its frequency can be synchronized by the input clock signal from the PLLIN pin. The typical switching frequency is 400kHz.
Here shows the typical application circuit for the LTM4607. The selection of external component is primarily determined by the maximum load current and output voltage. The value of the feedback resistor is 7.15K, so based on the equation, the output voltage is set to 12V. The PLLFLTR pin can be grounded to lower the frequency to 200kHz or tied to 2.4V to yield approximately 400kHz. Here the PLLFLTR and R FB are set as in buck mode. At buck mode, sensing resistor selection is based on the maximum output current and the allowed maximum sensing threshold 130mV.
Here is the configuration for boost mode. VIN = 5V to 12V, VOUT = 12V and f = 400kHz. At boost mode, sensing resistor selection is based on the maximum input current and the allowed maximum sensing threshold 160mV. Consider the safety margin about 30%, we can choose the sensing resistor as 7mΩ.In this application circuit, the ripple current ratio at all inputs is 30%, so the value of the inductor is selected as 3.3 µH. For the input capacitor, only minimum capacitors are needed to handle the maximum RMS current, since it is a continuous input current at boost mode.
The original, yet still common approach to buck-boost regulation is the SEPIC and flyback topologies. At low to moderate power, they are acceptable solutions but at high output power they become undesirable because of their bulkier size and higher heat dissipation. To improve on that design, a few years ago Linear Technology introduced the first high efficiency, high power and smaller solution, the LTC3780, a true buck-boost DC/DC regulator IC. Like any high-end analog function, the LTC3780 depends on a fine-tuned layout, careful component selection, and deep power supply design knowledge. It also requires several discrete components, as illustrated on the schematic. Most recently, further improvements were made to a buck-boost circuit, when Linear Technology introduced the buck-boost DC/DC µModule regulators: LTM4605, LTM4607, and LTM4609. With over 24 components housed in each µModule device, the layout is comprised of just the µModule, an inductor, and a few output capacitors. This family offers a simple, pin compatible, high efficiency, high power compact product for buck-boost voltage regulation.
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Introducing the Buck-Boost µModule Regulators
Introducing the Buck-Boost µModule Regulators <ul><li>Source: LINEAR TECHNOLOGY </li></ul>
Introduction <ul><li>Purpose </li></ul><ul><ul><li>To introduce µModule Buck-Boost Regulators from Linear Technology. </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>What is Buck-Boost Regulator? </li></ul></ul><ul><ul><li>Linear Technology’s product portfolio </li></ul></ul><ul><ul><li>Key features </li></ul></ul><ul><ul><li>Applications </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>11 pages </li></ul></ul>
What is a Buck-Boost Regulator? <ul><li>1) Steps down (Buck) V In when V Out is less than V In </li></ul><ul><li>2) Keeps output regulated when V In = V Out </li></ul><ul><li>3) Steps up (Boost) V In when V Out is more than V In </li></ul>V In V Out BUCK BOOST V In V Out V in V Out
The Buck-Boost µModule Regulator <ul><li>Triple-purpose, triple-mode high power, high efficiency DC/DC µModule </li></ul><ul><li>Wide V IN Range: 4.5V to 36V </li></ul><ul><li>Wide V OUT Range: 0.8V to 34V </li></ul><ul><li>5A DC (10A DC in Buck Mode) </li></ul><ul><li>Output Current sharing allows up to 2 devices for more output power </li></ul><ul><li>Up to 98% Efficiency </li></ul><ul><li>Phase-Lockable Selectable Fixed Frequency from 200kHz to 400kHz </li></ul><ul><li>Small, Low Profile Surface Mount LGA Package(15mm x 15mm x 2.8mm) </li></ul>
Three Pin Compatible µModule Regulators <ul><li>LTM4605 </li></ul><ul><ul><li>V In range (4.5V to 20V) </li></ul></ul><ul><ul><li>V Out range (0.8V to 16V) </li></ul></ul><ul><ul><li>Up to 98% Efficiency </li></ul></ul><ul><li>LTM4607 </li></ul><ul><ul><li>V In range (4.5V to 36V) </li></ul></ul><ul><ul><li>V Out range (0.8V to 24V) </li></ul></ul><ul><ul><li>Up to 98% Efficiency </li></ul></ul><ul><li>LTM4609 </li></ul><ul><ul><li>V In range (4.5V to 36V) </li></ul></ul><ul><ul><li>V Out range (0.8V to 34V) </li></ul></ul><ul><ul><li>Up to 98% Efficiency </li></ul></ul>
Evolution of the Buck-Boost Regulator SEPIC design compared to a synchronous Buck-Boost LTC3780 The µModule Regulator
Additional Resource <ul><li>For ordering µModule Buck-Boost Regulators , please click the part list or </li></ul><ul><li>Call our sales hotline </li></ul><ul><li>For more product information go to </li></ul><ul><ul><li>http://www.linear.com/pc/viewCategory.jsp?navId=H0,C1,C1003,C1042,C1424,C1788 </li></ul></ul><ul><li>Visit Element 14 to post your question </li></ul><ul><ul><li> www.element-14.com </li></ul></ul><ul><li>For additional inquires contact our technical service hotline or even use our “Live Technical Chat” online facility </li></ul>Newark Farnell