ОПИСАНИЕ

The LTC3129 is a high efficiency, 200mA buck-boost DC/DC converter with a wide VIN and VOUT range. It includes an accurate RUN pin threshold to allow predictable regulator turn-on and a maximum power point control (MPPC) capability that ensures maximum power extraction from non-ideal power sources such as photovoltaic panels.

The LTC3129 employs an ultralow noise, 1.2MHz PWM switching architecture that minimizes solution footprint by allowing the use of tiny, low profile inductors and ceramic capacitors. Built-in loop compensation and soft-start simplify the design. For high efficiency operation at light loads, automatic Burst Mode operation can be selected, reducing the quiescent current to just 1.3µA.

Additional features include a power good output, less than 10nA of shutdown current and thermal shutdown.

The LTC3129 is available in thermally enhanced 3mm × 3mm QFN and 16-lead MSOP packages.

 

ОСОБЕННОСТИ

Regulates VOUT Above, Below or Equal to VIN

Wide VIN Range: 2.42V to 15V, 1.92V to 15V After Start-Up (Bootstrapped)

Wide VOUT Range: 1.4V to 15.75V

200mA Output Current in Buck Mode

Single Inductor

1.3µA Quiescent Current

Programmable Maximum Power Point Control

1.2MHz Ultralow Noise PWM

Current Mode Control

Pin Selectable Burst Mode® Operation

Up to 95% Efficiency

Accurate RUN Pin Threshold

Power Good Indicator

10nA Shutdown Current

Thermally Enhanced 3mm × 3mm QFN and

16-Lead MSOP Packages

 

APPLICITIONS

Industrial Wireless Sensor Nodes

Post-Regulator for Harvested Energy

Solar Panel Post-Regulator/Charger

Intrinsically Safe Power Supplies

Wireless Microphones

Avionics-Grade Wireless Headsets

 

ОПЕРАЦИЯ

INTRODUCTION

The LTC3129 is a 1.3µA quiescent current, monolithic, current mode, buck-boost DC/DC converter that can operate over a wide input voltage range of 1.92V to 15V and provide up to 200mA to the load. Internal, low RDS(ON) N-channel power switches reduce solution complexity and maximize efficiency. A proprietary switch control algorithm allows the buck-boost converter to maintain output voltage regulation with input voltages that are above, below or equal to the output voltage. Transitions between the step-up or step down operating modes are seamless and free of transients and sub-harmonic switching, making this product ideal for noise sensitive applications. The LTC3129 operates at a fixed nominal switching frequency of 1.2MHz, which provides an ideal trade-off between small solution size and high efficiency. Current mode control provides inherent input line voltage rejection, simplified compensation and rapid response to load transients.

Burst Mode capability is also included in the LTC3129 and is user-selected via the PWM input pin. In Burst Mode operation, the LTC3129 provides exceptional efficiency at light output loading conditions by operating the converter only when necessary to maintain voltage regulation. The Burst Mode quiescent current is a miserly 1.3µA. At higher loads, the LTC3129 automatically switches to fixed frequency PWM mode when Burst Mode operation is selected.If the application requires extremely low noise, continuous PWM operation can also be selected via the PWM pin.

Oscillator

The LTC3129 operates from an internal oscillator with a nominal fixed frequency of 1.2MHz. This allows the DC/DC converter efficiency to be maximized while still using small external components.

Current Mode Control

The LTC3129 utilizes average current mode control for the pulse width modulator. Current mode control, both average and the better known peak method, enjoy some benefits compared to other control methods including: simplified loop compensation, rapid response to load transients and inherent line voltage rejection.

Average current mode control requires appropriate compensation for the inner current loop, unlike peak current mode control. The compensation network must have high DC gain to minimize errors between the actual and commanded average current level, high bandwidth to quickly change the commanded current level following transient load steps and a controlled mid-band gain to provide a form of slope compensation unique to average current mode control. The compensation components required to ensure proper operation have been carefully selected and are integrated within the LTC3129.