sc46166 Silan, sc46166 Datasheet - Page 4

• Manufacturer Part Number: sc46166
• Description: 300ma ,500khz High Efficiency Step-up Dc/dc Converter
• Manufacturer: Silan

current mode PWM operation,SC46166 automatically detects the output, if the output load current falls below an
internally programmed threshold (The threshold has an dependence on the input voltage, output voltage and also
the value of the external inductor.), it shifts to Power Saving Mode operation, in which the IC consumes only 20μA,
the efficiency is increased. However, the output ripple typically increases. Power Saving Mode ripple can be
reduced, by placing a small feed-forward capacitor (An empirical suggestion is around 0.1~10nF) between V
and FB pins.
reaches 150°C, the device shuts off entirely, the part will be enabled again when the die temperature drops by about
20°C.
APPLICATIONS INFORMATION
Output Voltage Setting
Feedback Loop Design
quiescent current consumption and interference immunity. Higher R reduces the quiescent current (Path current =
1.23V/R2), however resistors beyond 5MΩ , are not recommended. Lower R gives better noise immunity, and is
less sensitive to interference, layout parasitics, FB node leakage, and improper probing to FB pins. A proper value
of feed-forward capacitor C1 parallel with R1 can improve the noise immunity of the feedback loops, especially in
an improper layout. An empirical suggestion is around 100pF~1nF for feedback resistors of MΩ, and 10nF~100nF
for feedback resistors of hundreds kΩ.
COMPONENT SELECTION
Typically, a 4.7μH inductor is recommended for most applications. Larger values of inductance will allow greater
output current capability by reducing the inductor ripple current. Increasing the inductance above will also increase
size .
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
Http://www.silan.com.cn
Operating at heavy loads for a long time, the die temperature will rise, if the die temperature continues to rise and
Referring to the figure1, the output voltage of the switching regulator (V
Referring to Application Circuit of figure1, the selection of R1 and R2 are based on the trade-off between
The SC46166 can utilize small surface mount and chip inductors due to its fast 500kHz switching frequency.
Inductor Selection
V
OUT
=
(1
+
R2
R1
)X1.23V
OUT
) can be set with Equation following:
REV:1.2
SC46166
Page 4 of 11
2008.07.04
OUT