RT9266BPE RICHTEK [Richtek Technology Corporation], RT9266BPE Datasheet - Page 12

• Manufacturer Part Number: RT9266BPE
• Description: Tiny Package, High Efficiency, Step-Up DC/DC Converter
• Manufacturer: RICHTEK [Richtek Technology Corporation]

RT9266B
Application Information
Output Voltage Setting
Referring to application circuits, the output voltage of the
switching regulator (V
Feedback Loop Design
Referring to application circuits, The selection of R1 and
R2 based on the trade-off between quiescent current
consumption and interference immunity is stated below:
For applications without standby or suspend modes,
lower values of R1 and R2 are preferred. For applications
concerning the current consumption in standby or
suspend modes, the higher values of R1 and R2 are
needed. Such
sensitive to any interference, which require careful layout
and avoid any interference, e.g. probing to FB pin.
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12
Follow Equation (1).
Higher R reduces the quiescent current (Path current
= 1.25V/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 parallel with
R1 can improve the noise immunity of the feedback
loops, especially in an improper layout. An empirical
suggestion is around 0~33pF for feedback resistors of
MΩ, and 10nF~0.1μF for feedback resistors of tens to
hundreds kΩ.
V
OUT1
= ( 1+
Q
+
_
Prober Parasitics
R2
R1
“
high impedance feedback loops
) 1.25V
×
OUT
) can be set with Equation (1).
V
OUT1
R1
R2
FB Pin
”
are
(1)
Layout Guide
Board Layout Example (2-Layer Board)
(Refer to Application Circuit Figure 2 for the board)
A full GND plane without gap break.
V
for the 1mF MLCC capacitor between Pin5 and Pin3.
V
inductor, when VIN is not an idea voltage source.
Minimized FB node copper area and keep far away
from noise sources.
Minimized parasitic capacitance connecting to LX and
EXT nodes, which may cause additional switching loss.
DD
IN
to GND noise bypass
to GND noise bypass
- Bottom Layer -
- Top Layer -
−
−
Add a capacitor close to L1
Short and wide connection
DS9266B-09 March 2007