RT8055B 查看數據表（PDF） - Richtek Technology
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RT8055B Datasheet PDF : 13 Pages
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RT8055B
Typical Application Circuit
L1
VIN
5V
CIN
22µF
6
RT8055B
PVDD
LX 3, 4
2µH
R3
R4
100k
7 VDD
C1
FB 9
PGOOD
8 PGOOD COMP 10
CF
R1
22pF 75k
R2
24k
ROSC
180k
1 SHDN/RT
RCOMP
30k
2,11 (Exposed Pad) GND
5 PGND
CCOMP
470pF
VOUT1
3.3V/3A
COUT
22µF x 2
Note : Using X5R/X7R Ceramic Capacitors
VOUT
3.3
2.5
1.8
1.5
1.2
1.0
R1 (kΩ)
75
51
30
21
12
6
Table 1. Recommended Component Selsction
R2 (kΩ)
24
24
24
24
24
24
RCOMP (kΩ)
30
27
22
18
15
13
CCOMP (nF)
0.47
0.47
0.47
0.47
0.47
0.47
L1 (μH)
2.2
2.2
2.2
2.2
1.0
1.0
COUT (μF)
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
Functional Pin Description
Pin No.
Pin Name
Pin Function
Shutdown Control or Frequency Setting Input. Connect a resistor to ground from
1
SHDN/RT this pin sets the switching frequency. Force this pin to VDD or GND causes the
device to be shut down.
Signal Ground. All small-signal components and compensation components should
2,
GND
11 (Exposed Pad)
be connected to this ground, which in turn connects to PGND at one point. The
exposed pad must be soldered to a large PCB and connected to GND for maximum
power dissipation.
3, 4
LX
Internal Power MOSFET Switches Output. Connect this pin to the inductor.
5
PGND Power Ground. Connect this pin close to the negative terminal of CIN and COUT.
6
PVDD Power Supply Input. Decouple this pin to PGND with a capacitor.
7
VDD
Signal Supply Input. Decouple this pin to GND with a capacitor. Generally, VDD is
equal to PVDD.
8
PGOOD Power Good Indicator. The pin is an open drain logic output that is pulled to Ground.
Feedback Pin. This pin receives the feedback voltage from a resistive divider
9
FB
connected across the output.
Error Amplifier Compensation Point. The current comparator threshold increases
10
COMP with this control voltage. Connect external compensation elements to this pin to
stabilize the control loop.
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DS8055B-03 April 2011
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