FEATURES
NEW DMOS TOPOLOGY:
Ultra Low Dropout Voltage:
115mV Typ at 500mA and 3.3V Output
Output Capacitor NOT Required for Stability
FAST TRANSIENT RESPONSE
VERY LOW NOISE: 33μVrms
HIGH ACCURACY: ±2% max
HIGH EFFICIENCY:
IGND = 1mA at IOUT = 500mA
Not Enabled: IGND = 0.5μA
2.5V, 2.7V, 3.0V, 3.3V, 5.0V, AND ADJUSTABLE
OUTPUT VERSIONS
FOLDBACK CURRENT LIMIT
THERMAL PROTECTION
OUTPUT VOLTAGE ERROR INDICATOR(1)
SMALL SURFACE-MOUNT PACKAGES:
SOT223-5, DDPAK-5, SO-8

APPLICATIONS
PORTABLE COMMUNICATION DEVICES
BATTERY-POWERED EQUIPMENT
PERSONAL DIGITAL ASSISTANTS
MODEMS
BAR-CODE SCANNERS
BACKUP POWER SUPPLIES

DESCRIPTION
The REG103 is a family of low-noise, low-dropout, linear
regulators with low ground pin current. Its new DMOS
topology provides significant improvement over previous
designs, including low-dropout voltage (only 115mV typ at
full load), and better transient performance. In addition, no
output capacitor is required for stability, unlike conventional
low-dropout regulators that are difficult to compensate and
require expensive low ESR capacitors greater than 1μF.
Typical ground pin current is only 1mA (at IOUT = 500mA)
and drops to 0.5μA in not enabled mode. Unlike regulators
with PNP pass devices, quiescent current remains relatively
constant over load variations and under dropout conditions.
The REG103 has very low output noise (typically 33μVrms
for VOUT = 3.3V with CNR = 0.01μF), making it ideal for use
in portable communications equipment. On-chip trimming
results in high output voltage accuracy. Accuracy is maintained
over temperature, line, and load variations. Key
parameters are tested over the specified temperature range
(–40°C to +85°C).
The SO-8 version of the REG103 has an ERROR pin that
provides a power good flag, indicating the regulator is in
regulation. The REG103 is well protected—internal circuitry
provides a current limit that protects the load from
damage. Thermal protection circuitry keeps the chip from
being damaged by excessive temperature. In addition to the
SO-8 package, the REG103 is also available in the DDPAK
and the SOT223-5.