ISL95870HRUZ-T

The output voltage of the converter for the ISL95870 and ISL95870A controllers is set using resistor-programmed setpoint reference voltages that directly set the output voltage of the converter between 0.5V and 1.5V, and up to 5V with a feedback voltage divider. The voltage identification logic-inputs select four resistor-programmed setpoint reference voltages, allowing for dynamic selection of slew-rate controlled output voltages. The setpoint reference voltages use the naming convention V SET(x) where (x) is the first, second, third, or fourth setpoint reference voltage. The programmed resistors R SET1, RSET2, RSET3, and RSET4 are designed in a specific way to achieve the desired output voltage. The sum of all the programming resistors should be approximately 300k Ω for proper voltage regulation [1, 1+1, 1+1, 1+1, 1+1]. The ISL95870B controller has specific setpoint voltages for V SET2, V SET3, and V SET4, which are determined by Equations 22, 23, and 24 respectively. V SET1 is fixed at 0.5V and corresponds to the closure of internal switch SW0, configuring the V SET amplifier as a unity-gain voltage follower for the 0.5V voltage reference V REF. The relationship between the setpoint voltages and the output voltages is such that VSET1 < VSET2 < VSET3 < V SET4, and consequently, VOUT1 < VOUT2 < VOUT3 < VOUT4. The calculation of the programmed resistors R SET1, RSET2, and R SET3 is done using specific equations to achieve the desired output voltage [1, 1+1, 1+1, 1+1, 1+1].

The ISL95870, ISL95870A, and ISL95870B ICs are Single-Phase Synchronous-Buck PWM regulators featuring Intersil’s proprietary R4 Technology™, which allows for a wide 3.3V to 25V input voltage range, making them ideal for systems running on battery or AC-adapter power sources [1]. These controllers offer dynamically selected slew-rate controlled output voltages, with soft-start and dynamic setpoint slew-rates that are capacitor programmed [1]. Additionally, voltage identification logic-inputs select resistor-programmed setpoint reference voltages, allowing for direct setting of the output voltage of the converter between 0.5V and 1.5V, and up to 5V with a feedback voltage divider [1]. Compared to the R3 modulator, the R4 modulator in these controllers provides equivalent light-load efficiency and faster transient response [1]. For more detailed information on applications, schematics, and functional pin descriptions of the ISL95870, ISL95870A, and ISL95870B controllers, please refer to the respective device information page on intersil.com [1]. Additionally, the controllers feature a power-on reset mechanism that ensures the IC is disabled until the voltage at the VCC pin reaches a certain threshold, and start-up timing that enables the controller once specific thresholds are met, allowing for smooth operation and control of the output voltage [2]. [2].

The input voltage range for the ISL95870, ISL95870A, and ISL95870B PWM DC/DC controllers is 3.3V to 25V. [1]