Information
9
Portable Power Conversion Design Guide
DC/DC Conversion
Linear Regulators
Linear Regulators
Linear regulators provide a precise regulated voltage to the system load from a varying input voltage source. Compared to
switching regulators, they are generally smaller, simpler, and can benefit from reduced electrical noise. They are generally
less efficient than buck regulators, but for small voltage changes or low currents the absolute power losses may be small.
There are trade-offs when selecting the proper LDO. Regulation tolerance, dropout voltage, power supply ripple rejection
(PSRR), dynamic performance, quiescent current, power dissipation capability and protection features can be important
device capabilities. Microchip’s LDO product line can address a wide input voltage range with some LDOs capable of
withstanding 40V transients. We offer devices that consume ultra-low power with input quiescent currents as low as 20 nA;
disable load circuits for low-power standby operation using shutdown inputs; filter noisy inputs with PSRR as high as 90
dB; and enjoy robust operation with integrated over-current protection, short-circuit protection, high-temperature operation
capabilities, and over-temperature protection features.
MCP1703A Low Quiescent Current 16 V Low Dropout Linear Regulator
The MCP1703A is a CMOS, low dropout voltage regulator with 250 mA maximum output current. Working with voltages up
to 16V and consuming only 2 µA of quiescent current, it is an ideal solution for applications using 9V alkaline, Li-ion, or
multi-cell power sources. It is available in space-efficient SOT-23A and SOT-89 packages; or in a thermally capable 3-pin
SOT-223 and 8-pin 2 × 3 DFN.
MCP1703A Typical Application Circuit
■ Wide 2.7V to 16V input operating voltage range
■ Supports load currents up to 250 mA
■ Low 2.0 μA typical quiescent current
■ Low ground current when operating in dropout
■ Fast startup time
■ Low dropout voltage, 625 mV typical
@ 250 mA for VR = 2.8V
■ 0.4% Typical output voltage tolerance
■ Many standard output voltage options: 1.2V, 1.5V, 1.8V,
2.5V, 2.8V, 3.0V, 3.3V, 4.0V, 5.0V
■ Stable with 1.0 μF to 22 μF ceramic output capacitance
■ Short-circuit protection
■ Over-temperature protection
GND
V
IN
VOUT
IOUT
50 mA
V
OUT
3.3V
9V
Battery
CIN
1 μF
Ceramic
VIN
COUT
1 μF
Ceramic