RT8267GS 查看數據表（PDF） - Richtek Technology
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RT8267GS Datasheet PDF : 12 Pages
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RT8267
Table 1. Recommended Component Selection
VOUT (V)
12
R1 (kΩ)
88.7
R2 (kΩ)
10
RC (kΩ)
62
5
30
10
20
3.3
17
10
10
2.5
10.45
10
7.5
1.8
4.75
10
6
1.222
0
10
6
CC (nF)
0.82
2.2
1.5
1.5
1.5
3.9
COUT (μF)
22
22
22
22
22
22
L1 (μH)
33
22
15
10
10
6.8
Functional Pin Description
Pin No.
1
2
3
Pin Name
BOOT
VIN
SW
Pin Function
High Side Gate Drive Boost Input. BOOT supplies the drive for the high side
N-MOSFET switch. Connect a 10nF or greater capacitor from SW to BOOT to power
the high side switch.
Power Input. VIN supplies the power to the IC, as well as the step-down converter
switches. Bypass VIN to GND with a suitable large capacitor to eliminate noise on the
input to the IC.
Power Switching Output. SW is the switching node that supplies power to the output.
Connect the output LC filter from SW to the output load. Note that a capacitor is
required from SW to BOOT to power the high side switch.
4
GND
Ground. The exposed pad must be soldered to a large PCB and connected to GND for
maximum power dissipation.
5
FB
Feedback Input. FB senses the output voltage to regulate said voltage. The feedback
reference voltage is 1.222V typically.
Compensation Node. COMP is used to compensate the regulation control loop.
6
COMP
Connect a series RC network from COMP to GND to compensate the regulation control
loop. In some cases, an additional capacitor from COMP to GND is required.
7
EN
Enable Input. EN is a digital input that turns the regulator on or off. Drive EN higher than
1.4V to turn on the regulator, lower than 0.4V to turn it off. If the EN pin is open, it will be
pulled to high by internal circuit.
8
NC
No Internal Connection.
Function Block Diagram
VIN
VCC
1µA
Internal
Regulator
Oscillator
400kHz/120kHz
Current Sense
Slope Comp Amplifier
+
-
10k
EN
VA VCC
-
Foldback
Control
1V +
0.6V +
3V
Shutdown
Comparator
-
UV
Comparator
SQ
+
RQ
-
Current
1.222V +
EA
-
Comparator
Gm = 780µA/V
VA
BOOT
SW
GND
www.richtek.com
2
FB
COMP
DS8267-02 March 2011
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