Boost 3 Click Board™

HOow Does The Boost 3 Click Board™ Work?

The Boost 3 Click Board™ is based on the TPS61391, a 700-kHz pulse-width modulating (PWM) Step-Up converter with a 70V switch FET with an input voltage up to 5.5 V from Texas Instruments. It supports an input voltage up to 5.5V and operates at a 700 kHz pulse-width modulation (PWM) crossing the whole load range. There are two ratio options for the current proportional to the APD current: MON1 (4:5) and MON2 (1:5). By connecting an additional RC filter for low ripple applications from the mirror output pins to the GND, the current flowing through the APD is converted into the voltage crossing the resistor from MON1/MON2 pins to GND. Additionally, a high power optical protection, with the response time typically of 0.5 μs, is integrated by clamping the pre-set current limit (program by the R6 resistor) and could recover automatically when the high optical power is removed.

The output voltage of the TPS61391 is externally adjustable using a resistor divider network. The relationship between the output voltage and the resistor divider is given by the equation:

VOUT = ( VREF + 0.1V ) * ( 1 + ( VR1 + R8 ) / R9 ) [V]

where VREF has a typical value of 1.2V. When the potentiometer has a 0V value, the output voltage has its minimum value of 20V. Increasing the resistance of a potentiometer and reaching its maximum value of 500kΩ, the output voltage also reaches its maximum value of 70V. The potentiometer featured on the Boost 3 Click Board™ can change the feedback thus influencing a change in the output voltage. This makes the Click board™ extremely practical because you can, with a simple turn of the potentiometer, get the wide voltage range.

The Boost 3 Click Board™ communicates with MCU using only one GPIO pin routed on the CS pin of the mikroBUS™ socket labeled as EN. An under-voltage lockout (UVLO) circuit stops the operation of the converter when the input voltage drops below the typical UVLO threshold of 2.5 V. When the input voltage is above the maximal UVLO rising threshold of 2.5 V, and the EN pin is pulled above the high threshold (1.2V minimum), the TPS61391 is enabled. When the EN pin is pulled below the low threshold (0.4 maximum), the device goes into Shutdown Mode.

It also possesses the output terminal labeled as APD used for biasing and monitoring the avalanche photodiodes (APD) and high optical power protection. There is an additional FET in series of power path connecting with the APD output terminal. When the current flowing through the external APD exceeds the short protection threshold, set by connecting the resistor from R6 to the ground, the on-resistance of the internal FET becomes larger to clamp the current within the protection threshold by lowering the APD bias voltage. It takes typically 0.5μs for the FET to respond in case of high optical power occurring. When the high optical power condition releases, the TPS61391 recovers automatically back to the Normal Operation Mode.

The Boost 3 Click Board™ is designed to be operated with both 3.3V and 5V logic voltage levels that can be selected via VCC SEL jumper. This allows for both 3.3V and 5V capable MCUs to use the GPIO communication line properly. However, the Click board™ comes equipped with a library that contains easy to use functions and an example code that can be used as a reference for further development.

SPECIFICATIONS

Pinout Diagram

This table shows how the pinout of the Boost 3 Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
NC	1	AN	PWM	16	NC
NC	2	RST	INT	15	NC
Device Enable	CS	3	CS	RX	14	NC
NC	4	SCK	TX	13	NC
NC	5	MISO	SCL	12	NC
NC	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

ONBOARD SETTINGS AND INDICATORS

BOOST 3 CLICK ELECTRICAL SPECIFICATIONS