ISL8104CRZ

ISL8104CRZ Application Field and Working Principle

The ISL8104CRZ is a high-performance, step-down, dc-to-dc switching controller designed for powering applications from battery source. It integrates a voltage regulator initializing at a preset voltage with a high-side power MOSFET, a synchronous rectifier driver, an on-time gap generator, an integrated high-accuracy current sense amplifier, a soft start/tracking/enable pin, and multiple safety/ sequencing functions. The ISL8104CRZ is optimized to reduce the external component count, board space, and power dissipation.

The integrated voltage regulator of the ISL8104CRZ is designed to provide a stable output voltage. The regulator establishes a feedback loop to monitor the output voltage and compare with a predetermined reference voltage. When the monitored output voltage is higher than the threshold voltage, the voltage regulator will reduce the output voltage by either increasing the off-time (converting to pulse skipping) or decreasing the pulse width, consequently reducing the output power.

The power output of the ISL8104CRZ is regulated by the MOSFET, which is switched on and off based on the enable and sync pins. The enable pin controls the high-side MOSFET allowing it to switch on when a logic high voltage is applied to the enable pin. The sync pin synchronizes the on and off switching times of the MOSFET. The synchronous rectifier is controlled by the SRD control pin, which when pulled low allows the MOSFET to switch off and the synchronous rectifier to conduct. This unique design of the ISL8104CRZ efficiency is improved as heat directed towards the ground and away from the battery is dissipated through the synchronous rectifier.

The ISL8104CRZ is easy to configure using an external resistor and diode to set the output voltage, frequency, and other parameters. Its simple power supply design controls the voltage and current delivered to the load. The flexible application programming and control features of the ISL8104CRZ make it the ideal controller for a wide variety of battery-powered applications such as cell phones, PDAs, MP3 players, digital cameras, GPS receivers, and other portable products.

Application Field

The ISL8104CRZ is primarily designed for on-the-fly voltage adjustment in portable applications. It is a high-performance, step-down, dc-to-dc switching controller suitable for powering a wide range of portable devices and applications, such as cell phones, PDAs, digital cameras, and GPS systems. It provides high efficiency, fast transient response, and a high level of safety and protection. The ISL8104CRZ can also be used in Li-ion/ Li-poly applications to charge the battery or power the system.

Working Principle

The working principle of the ISL8104CRZ is based on the principle of pulsewidth modulation (PWM). PWM is used for controlling the output voltage of the device, which is regulated through regulating the on and off times of the MOSFET. The output voltage is regulated based on the feedback provided by the reference voltage sense (VSENSE). When the monitored output is higher than the threshold voltage, the PWM circuitry responds by reducing the output voltage by either increasing the off-time (converting to pulse skipping) or decreasing the pulse width.

The power output of the ISL8104CRZ is regulated by the MOSFET, which is switched on and off based on the enable and sync pins. The enable pin controls the high-side MOSFET allowing it to switch on when a logic high voltage is applied to the enable pin. The sync pin is used to synchronize the on and off switching times of the MOSFET. The synchronous rectifier is controlled by the SRD control pin, which when pulled low allows the MOSFET to switch off and the synchronous rectifier to conduct, thus dissipating heat away from the battery and towards the ground.

The ISL8104CRZ also features an on-time gap generator, a soft-start/tracking/enable pin, multiple safety/sequencing functions, and an integrated current sense amplifier to monitor the output current. The highly integrated design of the ISL8104CRZ provides efficient utilization of board space and low power dissipation.