The Buck-boost converter is a DC/DC converter that steps up (or) down voltage by producing a voltage equivalent to or lower or higher than the input voltage. This converter merges the buck converter and a boost converter functions. This converter has an output voltage magnitude that is either below or above the input voltage’s magnitude. So it is equal to a Fly-back converter with a single inductor instead of a transformer. A buck-boost converter which provides a 12 V output using a 12 V battery. So this battery’s voltage can change from 10 V to 14.7 V. This article elaborates on LTC3442 IC, pin-out, specifications, and its applications.
What is LTC3442 IC?
The LTC3442 is a buck-boost DC/DC converter with fixed frequency and is highly efficient, available in a 12-lead low profile and thermally enhanced DFN package. This IC works by simply adjusting the output voltage to be below, above (or) equivalent to the input voltage. It uses a continuous transfer function topology with all operating modes which makes the converter IC perfect for a single Li-ion (or) multi-cell alkaline applications wherever the output voltage is in the battery voltage range.
This buck boost DC/DC converter IC has two 0.10Ω N-channel MOSFET switches & two 0.10Ω P-channel switches. So its operating frequency & average input current limit can be programmed through an external resistor. LTC3442 converter IC’s quiescent current is 35µA only in burst mode operation which increases battery life within portable applications. This mode of operation simply allows the operator to program the load current mainly for Burst.
How LTC3442 IC Works?
The LTC3442 buck-boost DC/DC converter IC works by combining a variety of electronic components into a semiconductor material. So the components are interconnected by a complex network and are fixed onto the surface of the chip. The LTC3442 IC gives four different automatic operations which provide high efficiency output. Thus this converter IC uses only <1μA shutdown current with 35 μA Quiescent current in burst mode operation.
The LTC3442 IC utilizes a switch & diode for controlling the current flow throughout a capacitor & inductor. Whenever the switch is turned ON then energy can be stored within the inductor and the energy is transmitted to the output whenever the switch is turned off.
LTC3442 IC Pin Configuration:
The LTC3442 IC pin configuration is shown below. So this IC includes 12 pins which are explained below.
LTC3442 IC Pin Configuration
- Pin-1(SHDN/SS): This pin enables or disables an integrated circuit or it puts a device into low-power shutdown mode.
- Pin-2(RT): This pin can be connected using different methods based on the chip and the preferred output.
- Pin-3(SGND): It is the signal ground connection pin, used as a reference mainly for other signals like the soft start, enable voltages, and internal voltage reference.
- Pin-4(SW1): The SW1 pin is a switch signal input pin that decides whether the chip is in active mode or standby mode.
- Pin-5 (PGND): It is a power ground pin that carries high pulsed currents like those from a power driver stage or a power transistor.
- Pin-6(SW2): This pin can be utilized to disable a device within an on-off switch circuit. So this pin can be connected to a push-button switch that deactivates the device whenever it is pressed.
- Pin-7(BURST): This pin is utilized to set the burst mode level. So a resistor is connected between the burst pin & GND to set the burst mode threshold.
- Pin-8(VOUT): The VOUT pin of an IC that drives the gate terminal of the external N-MOSFET pass element directly.
- Pin-9(VIN): It is a power-supply pin that simply connects to the power rails of the circuit.
- Pin-10(RLIM): This pin adjusts the power switch current limit & the ROSC pin.
- Pin-11(VC): This is the power supply pin IC that works in the applied voltage to it which is used typically for both CMOS devices & bipolar junction transistors.
- Pin-12(FB): This is the voltage feedback pin of the IC that samples voltage to control the CV of the circuit.
Equivalents & Alternatives:
Equivalent:- LTC3442 ICs are; LTC3440, LTC3441,LTC3447, etc. So, alternative to LTC3442 ICs are; LM2596, LM5118, XY-SK80, LM317, LT8640EUDC, TPS61200DRCT, XY-S3580, etc.
Buck Boost Converter Circuit with LTC3442 IC
A buck-boost converter circuit with LTC3442 IC is shown below that provides 3.3Volts output at highest current rating from batteries input. So this IC has automatic burst mode operation which drives the output voltage & current either below or above the input voltage & current. So its input voltage ranges from 2.4V to 5.5V whereas the output voltage ranges from 2.4Volts to 5.25Volts.
The required components to make this circuit mainly include; LTC3442 IC, resistors like; 1MΩ, 15KΩ, 75KΩ, 340KΩ, 200KΩ & 2.2KΩ, electrolyte capacitors like; 10µF & 22µF, 4.7µH inductor, 3.7V Li-ion battery and ceramic capacitors like; 0.01µF , 220pF & 470pF. So, connect this circuit as per the diagram shown below.
Buck Boost Converter Circuit with LTC3442 IC
Working
The LTC3442 IC in the above circuit provides different operations that provide high-efficiency output. So this circuit simply maintains the o/p at 3.3V which may be below or above the input voltage. So the automatic burst mode operation of this IC changes operating modes when the load current changes. Thus. it maintains high efficiency without any required commands from a host. Here, the operating frequency & average input current limit with an external resistor can be programmed. Thus, this converter circuit can also maintain regulation in load transients, whenever the battery ESR may cause the input voltage to fall under 3.3Volts momentarily.
Advantages & Disadvantages
The advantages of LTC3442 IC include the following.
- The LTC3442 is a highly efficient IC with a fixed frequency.
- It provides four different automatic operations to provide high-efficiency output.
- It has a low quiescent current in burst mode operation like 35µA only, which maximizes battery life.
- This IC is available in a low profile.
- The topology of LTC3442 IC provides a constant transfer function throughout all operating modes.
- The operating frequency & average input current limit of this IC can be programmed through an external resistor.
- This IC has an automatic burst mode that can be controlled or programmed manually.
- It doesn’t need any Schottky diodes but requires a single inductor.
The disadvantages of LTC3442 IC include the following.
- These converter’s design & implementation are difficult, particularly for systems that need high power & efficiency.
- These converters produce output voltage by reverse polarity that may restrict their utilization within certain applications.
- The switch within a buck-boost converter doesn’t include a GND terminal which is difficult with the driving circuitry.
- The fast switching of this converter IC can produce EMI, so that may need effective filtering & shielding measures.
- These are expensive and have switching noise, etc.
Applications
The applications of LTC3442 IC include the following.
- These converter ICs are utilized in battery chargers for mobile phones, power banks, laptops, etc.
- These ICs are utilized in SMPS (switch-mode power supplies), X-ray machines, etc.
- These converter ICs are utilized for motherboards and PCs.
- Buck-boost converter ICs are used in solar chargers, adaptive control & power audio amplifier applications.
- These are fundamental components within electric vehicles, wherever various electronic circuits work at different voltage levels.
- These are utilized in power delivery networks for military unmanned aerial vehicles, drones, etc.
- LTC3442 IC is used in handheld computers, PDA/SMART phones, MP3 players, wireless handsets, USB peripherals, digital cameras, digital cameras, handheld instruments, USB peripherals, etc.
Please refer to this link for the LTC3442 IC datasheet.
Thus, this is an overview of the LTC3442 buck-boost DC/DC converter IC, pin-out, features, specifications, circuit, working, and its uses. So the main features of this IC mainly include; fixed frequency, automatic programmable input current limit, burst mode, low quiescent current, peak current limit, and thermal shutdown. This is a highly efficient IC, used in different applications wherever the output voltage is in the battery voltage range like alkaline or lithium-ion batteries. Thus, here is a question for you, what is LM5118 IC?