DESCRIPCIÓN GENERAL

The ADP5075 is a high performance dc-to-dc inverting regulator used to generate negative supply rails. The input voltage range of 2.85 V to 15 V supports a wide variety of applications. The integrated main switch enables the generation of an adjustable negative output voltage down to 39 V below the input voltage. The ADP5075 operates at a pin selected 1.2 MHz/2.4 MHz switching frequency. The ADP5075 can synchronize with an external oscillator from 1.0 MHz to 2.6 MHz to ease noise filtering in sensitive applications. The regulator implements programmable slew rate control circuitry for the MOSFET driver stage to reduce electromagnetic interference (EMI).The ADP5075 includes a fixed internal or resistor programmable soft start timer to prevent inrush current at power-up. During shutdown, the regulator completely disconnects the load from the input supply to provide a true shutdown.

 

CARACTERÍSTICAS

Wide input voltage range: 2.85V to 15 V

Adjustable negative output to VIN − 39 V

Integrated 800 mA main switch

1.2 MHz/2.4 MHz switching frequency with optional external

frequency synchronization from 1.0 MHz to 2.6 MHz

Resistor programmable soft start timer

Slew rate control for lower system noise

Precision enable control

UVLO, OCP, OVP, and TSD protection

1.61 mm × 2.18 mm, 12-ball WLCSP

−40°C to +125°C junction temperature range

Supported by the ADIsimPower tool set

 

APLICACIONES

Bipolar amplifiers, analog-to-digital converters (ADCs),

digital-to-analog converters (DACs), and multiplexers

Charge coupled device (CCD) bias supplies

Optical module supplies

Radio frequency (RF) power amplifier (PA) bias

 

PWM MODE

The inverting regulator in the ADP5075 operates at a fixed frequency set by an internal oscillator. At the start of each oscillator cycle, the MOSFET switch turns on, applying a positive voltage across the inductor. The inductor current (IINDUCTOR) increases until the current sense signal crosses the peak inductor current threshold that turns off the MOSFET switch; this threshold is set by the error amplifier output. During the MOSFET off time, the inductor current declines through the external diode until the next oscillator clock pulse starts a new cycle. The ADP5075 regulates the output voltage by adjusting the peak inductor current threshold.

 

PSM MODE

During light load operation, the regulators can skip pulses to maintain output voltage regulation. Skipping pulses increases the device efficiency.

 

UNDERVOLTAGE LOCKOUT (UVLO)

The undervoltage lockout circuitry monitors the AVIN pin voltage level. If the input voltage drops below the VUVLO_FALLING threshold,the regulator turns off. After the AVIN pin voltage rises above the VUVLO_RISING threshold, the soft start period initiates, and the regulator is enabled.

 

INTERNAL REGULATORS

The internal VREG regulator in the ADP5075 provides a stable power supply for the internal circuitry. The VREG supply provides a high signal for device configuration pins but must not be used to supply external circuitry.The VREF regulator provides a reference voltage for the inverting regulator feedback network to ensure a positive feedback voltage on the FB pin.A current-limit circuit is included for both internal regulators to protect the circuit from accidental loading.

 

CURRENT-LIMIT PROTECTION

The inverting regulator in the ADP5075 includes current-limit protection circuitry to limit the amount of forward current through the MOSFET switch.When the peak inductor current exceeds the overcurrent limit threshold for a number of clock cycles during an overload or short-circuit condition, the regulator enters hiccup mode. The regulator stops switching and then restarts with a new soft start cycle after tHICCUP and repeats until the overcurrent condition is removed.

 

OVERVOLTAGE PROTECTION

An overvoltage protection mechanism is present on the FB pin for the inverting regulator.When the voltage on the FB pin drops below the VOV threshold, the switching stops until the voltage rises above the threshold.This functionality is enabled after the soft start period has elapsed.