feature

1.5A Minimum Guaranteed Output Current

1.5 ms maximum dropout rate

Suitable for 2.5V to 1.8V or 1.65V conversion

Suitable for 3.0V to 2.5V conversion

Current Limit and Thermal Shutdown

External shutdown control (FAN1951 only)

Error flag output (FAN1951 only)

fast transient response

Low ground current

application

Universal conversion for low voltage CPUs,

Digital Signal Processors and FPGAs

SMPS post regulator

Cable/Satellite STB

PCI Graphics Adapter Card

General Instructions

FAN1950 and FAN1951 are 1.5A low dropout linear

Regulators with Low Voltage, High Current Output

Minimal use of external components. Both devices use a PNP output pass-through element to achieve a maximum leakage of 500mV at 15A load current. In addition the device provides over current limiting and thermal shutdown features to ensure adequate protection. The FAN1951 provides a logic level enable pin and an error flag output to indicate undervoltage and overcurrent conditions. 1.8V and 2.5V fixed output versions are available. 3.3V, 1.65V and 1.5V options are available upon request.

Absolute Maximum Ratings Absolute maximum ratings are values beyond which the device may be damaged or have its useful life impaired. Functional operation under these conditions is not implied.

Electrical Specifications

(VIN=VOUT+1V, VIN=2.5V, Tj=+25°C unless otherwise specified) Indicates specifications that apply over the entire operating temperature range.

notes:

1. See Thermal Regulation Specifications for output voltage changes due to heating effects. Load and line regulation are measured at constant junction temperature with low duty cycle pulse tests.

2. Line and load regulation guarantees maximum power dissipation. Power dissipation is determined by input/output differential and output current. Guaranteed maximum output power will not be available over the full input/output voltage range.

3. Output voltage: When the output voltage is reduced to 98%, the output voltage is: VIN=VOUT+1V When the voltage is lower than 2.25V, the voltage drop is the input and output voltage difference, and the minimum input voltage is 2.25V. The minimum input operating voltage is 2.25V.

4. The flag output cannot be pulled to a voltage higher than the VIN

Typical Performance Characteristics (continued)

Typical Performance Characteristics (continued)

Input and output capacitors require a 4.7µF or larger input capacitor (ceramic or tantalum) installed in this part for stability, better transient response, noise and ripple rejection. Higher value if the bulk capacitor of the power supply is located 3-4 inches from the device or loads that require a large and fast rise time. The FAN1950 and FAN1951, as most LDO regulators, require an output capacitor. The recommended value for this capacitor is 10µF in thickness. Larger capacitors will additionally improve transient response, ripple rejection and output noise. Low-ESR tantalum capacitors are best suited for this application: they provide stable operation with good transient response over temperature. Using ceramic capacitors as output capacitors can cause instability (oscillating output voltage). Aluminum electrolytic capacitors can also be used for their ESR below 3Ω.

Mechanical Size 5 Wire to -252 DPAK Package