DESCRIPCIÓN

The LT3090 is a 600mA, low dropout negative linear regulator that is easily parallelable to increase output current or spread heat on surface mounted boards.  Designed with a precision current reference followed by a high performance rail-to-rail voltage buffer, this regulator finds use in applications requiring precision output, high current with no heat sink, output adjustability to zero and low dropout voltage. The device can also be configured as a 3-terminal floating regulator.

The LT3090 features fast transient response, high PSRR and output noise as low as 18µVRMS. The LT3090 generates a wide output voltage range (0V to –32V) while maintaining unity gain operation. This yields virtually constant bandwidth, load regulation, PSRR and noise, regardless of the programmed output voltage.

The LT3090 supplies 600mA at a typical dropout voltage of 300mV. Operating quiescent current is nominally 1mA and drops to << 1µA in shutdown. A single resistor adjusts the LT3090’s precision programmable current limit. The LT3090’s positive or negative current monitor either sources a current (0.5mA/A) or sinks a current (1mA/A) proportional to output current. Built-in protection includes reverse output protection, internal current limit with fold back and thermal shutdown with hysteresis.

 

CARACTERÍSTICAS

Output Current: 600mA

Single Resistor Sets Output Voltage

50µA SET Pin Current: ±1% Initial Accuracy

Límite de corriente programable

Positive or Negative Output Current Monitor

Parallelable for Higher Current and Heat Spreading

Low Dropout Voltage: 300mV

Low Output Noise: 18µVRMS (10Hz to 100kHz)

Configurable as 3-Terminal Floating Regulator

Wide Input Voltage Range: –1.5V to –36V

Rail-to-Rail Output Voltage Range: 0V to –32V

Positive/Negative Shutdown Logic or UVLO

Programmable Cable Drop Compensation

Load Regulation: 1.2mV (1mA to 600mA)

Stable with 4.7µF Minimum Output Capacitor

Stable with Ceramic or Tantalum Capacitors

Thermally Enhanced 12-Lead MSOP and 10-Lead 0.75mm × 3mm × 3mm DFN Packages

 

APLICACIONES

Post Regulator for Switching Supplies

Low Noise Instrumentation and RF Supplies

Rugged Industrial Supplies

Fuentes de alimentación de precisión

 

INFORMACIÓN SOBRE APLICACIONES

The LT3090 is a 600mA, rail-to-rail output, negative low dropout linear regulator featuring very low output noise, high bandwidth, precision programmable current limit, precision positive or negative current monitor, and bidirectional shutdown. The LT3090 supplies 600mA at a typical dropout voltage of 300mV. Unlike other devices, the LT3090 does not require a separate supply to achieve low dropout performance. The 1mA quiescent current drops to well below 1µA in shutdown.

The LT3090 is easy to use and incorporates all of the protection features expected in high performance regulators. Included are short circuit protection, safe operating area protection, as well as thermal shutdown with hysteresis. In bipolar supply applications where the regulator’s load is returned to a positive supply, OUT can be pulled above GND up to 36V and still allow the LT3090 to safely startup.

Output Voltage

The LT3090 incorporates a zero TC 50µA reference current source that flows into the SET pin. The SET pin is the inverting input of the error amp. Connecting a resistor from SET to ground generates a voltage that becomes the reference point for the error amplifier. The reference voltage is a straight multiplication of the SET pin current and the resistor value (Ohm’s Law, V = I • R). The rail-to-rail error amp’s unity gain configuration produces a low impedance voltage on its noninverting input, i.e. the OUT pin. Output voltage is programmable from 0V (using zero Ω resistor) to VIN plus dropout.

Stability and Input Capacitance

The LT3090 is stable with a minimum of 4.7µF capacitor placed at the IN pin. Low ESR ceramic capacitors can be used. However, in cases where long wires connect the power supply to the LT3090’s input and ground, the use of low value input capacitors combined with a large output load current may result in instability. The resonant LC tank circuit formed by the wire inductance and the input capacitor is the cause and not because of LT3090 instability.