Demonstration circuit 2815A features the LT3120, as wide operating range synchronous monolithic buck-boost converter with programmable output current limit.
The DC2815A demo board has four user selectable operating modes:
- An accurate programmable EN/UVLO pin which is used to ENABLE the converter (JP1).
- Programmable MPPC (Maximum Power Point Control) for Input Regulation Set Point (JP2).
- Burst Mode® operation and External CLK/Fixed Frequency PWM (JP3).
- Programmable Output Average Current Limit Set Point (JP4).
The LT3120 uses average current mode control to simplify voltage loop compensation and provide good line and load transient response.
The DC2815A operates with a 2.5V to 26V input voltage range. The demo board has been designed with the output voltage set to 5V. The LT3120 incorporates a proprietary low noise switching algorithm which optimizes efficiency with input voltages above, below or equal to the output voltage and ensures seamless transitions between operating modes.
In PWM mode, the switching frequency can operate between 400kHz to 2MHz by programming the RT resistor R5. LT3120 can be synchronized to an External CLK provided RT is programmed 25% to 50% below the synchronization frequency.
The LT3120 has an optional programmable current limit that can be used to control the output current. The current limit circuit requires an external sense resistor connected between ISP and ISN and the current limit value can be set by adjusting R6 and C26 connected to PROG pin.
LT3120 also has programmable MPPC feature to set the input regulation voltage and can be adjusted by changing R13, R14 and C28.
The LT3120 data sheet has detailed information about the operation, specifications, and applications of the part. The data sheet should be read in conjunction with the DC2815A quick start guide.
