Datasheet MIC4680 (Microchip) - 10

Micrel, Inc. MIC4680 Applications Information
Adjustable Regulators
Adjustable regulators require a 1.23V feedback signal.
Recommended voltage-divider resistor values for
common output voltages are included in Figure 1b.
For other voltages, the resistor values can be
determined using the following formulas: V IN ⎛ R1 ⎞
VOUT = VREF ⎜
+ 1⎟
⎝ R2
⎠ 2 MIC4680BM
IN
SW L1 3 R1 CIN
SHUTDOWN
ENABLE 1 SHDN FB 4 GND ⎛V
⎞
R1
R1 = R2⎜⎜ OUT − 1⎟⎟ , R2 =
V
OUT
⎝ VREF
⎠
−1
VREF VOUT D1 R2 COUT 5–8 Figure 1a. Adjustable Regulator Circuit VREF = 1.23V VOUT R1*† R2*† 1.8V 3.01k 6.495k 2.5V 3.01k 2.915k 3.3V 3.01k 1.788k 5.0V 3.01k 982Ω 6.0V 3.01k 776Ω * CIN D1 L1 COUT 68µH 1.5A
2A 60V Schottky
15µF 35V
AVX TPSE156035R0200 B260A Vishay-Diode, Inc***
or
SS26 General Semiconductor Coiltronics UP2B-680
or
Sumida CDRH125-680MC**
or
Sumida CDRH124-680MC** 220µF 10V
AVX TPSE227010R0060 All resistors 1% ** Shielded magnetics for low RFI applications *** Vishay-Diode, Inc. (805) 446-48600 † Nearest available resistor values Figure 1b. Recommended Components for Common Output Voltages March 2008 10 M9999-032808