Descripción

The TLV62565/6 devices are synchronous step-down converters optimized for small solution size and high efficiency. The devices integrate switches capable of delivering an output current up to 1.5 A.
The devices are based on an adaptive on time with valley current mode control scheme. Typical operating frequency is 1.5 MHz at medium to heavy loads. The devices are optimized to achieve very low output voltage ripple even with small external components and feature an excellent load transient response.
During light load, the TLV62565/6 automatically enter into Power Save Mode at the lowest quiescent current (50 μA typ) to maintain high efficiency over the entire load current range. In shutdown, the current consumption is reduced to less than 1 μA.
The TLV62565/6 provide an adjustable output voltage via an external resistor divider. The output voltage start-up ramp is controlled by an internal soft start, typically 250 µs. Power sequencing is possible by configuring the Enable (TLV62565) and Power Good (TLV62566) pins. Other features like over current protection and over temperature protection are built in. The TLV62565/6 devices are available in a SOT23 5-pin package.

 

Características

• 2.7-V to 5.5-V Input Voltage Range
• 1.5-MHz Typical Switching Frequency
• Output Current up to 1.5 A (Max)
• Adaptive On-Time Current Control
• Power Save Mode for Light Load Efficiency
• 50-µA Operating Quiescent Current
• Upto95%Efficiency
• Over Current Protection
• 95%Maximum Duty Cycle
• Excellent AC and Transient Load Response
• Power Good Output, TLV62566
• Internal Soft Startup of 250 µs (Typ)
• Adjustable Output Voltage
• Thermal Shutdown Protection
• Available in SOT-23 5-Pin Package

 

Aplicaciones

• Portable Devices
• DSLModems
• Hard Disk Drivers
• Set Top Box
• Table

 

Visión general

The TLV62565/6 device family includes two high-efficiency synchronous step-down converters. Each device operates with an adaptive on-time control scheme, which is able to dynamically adjust the on-time duration based on the input voltage and output voltage so that it can achieve relative constant frequency operation. The device operates at typically 1.5-MHz frequency pulse width modulation (PWM) at moderate to heavy load currents. Based on the VIN/VOUT ratio, a simple circuit sets the required on time for the high-side MOSFET. It makes the switching frequency relatively constant regardless of the variation of input voltage, output voltage, and load current. At the beginning of each switching cycle, the high-side switch is turned on and the inductor current ramps up to a peak current that is defined by on time and inductance. In the second phase, once the on time expires, the high-side switch is turned off while the low-side switch is turned on. The current through the inductor then decays until triggering the valley current level determined by the output of the error amplifier. Once this occurs, the on timer is set to turn the high-side switch back on again and the cycle is repeated.
The TLV62565/6 device family offers excellent load transient response with a unique fast response constant ontime valley current mode. The switching frequency changes during load transition so that the output voltage comes back in regulation faster than a traditional fixed PWM control scheme. Internal loop compensation is integrated which simplifies the design process while minimizing the number of external components. At light load currents the device automatically operates in Power Save Mode with pulse frequency modulation (PFM).

 

Soft Start

After enabling the device, internal soft-start circuitry monotonically ramps up the output voltage which reaches nominal output voltage during a soft-start time of 250 µs (typical). This avoids excessive inrush current and creates a smooth output voltage rise slope. It also prevents excessive voltage drops of primary cells and rechargeable batteries with high internal impedance.
If the output voltage is not reached within the soft-start time, such as in the case of a heavy load, the converter enters regular operation. The TLV62565/6 are able to start into a pre-biased output capacitor. The converter starts with the applied bias voltage and ramps the output voltage to its nominal value.