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參數(shù)資料
| 型號(hào)： | RT9203GS |
| 廠商： | Richtek Technology Corporation |
| 英文描述： | Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller |
| 中文描述： | 雙穩(wěn)壓器-同步降壓PWM型DC - DC和線性控制器 |
| 文件頁(yè)數(shù)： | 13/16頁(yè) |
| 文件大小： | 228K |
| 代理商： | RT9203GS |
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RT9203/A
Preliminary
13
DS9203/A-10 March 2007
www.richtek.com
Input / Output Capacitor
High frequency/long life decoupling capacitors should be
placed as close to the power pins of the load as physically
possible. Be careful not to add inductance to the PCB
trace, as it could eliminate the performance from utilizing
these low inductance components. Consult with the
manufacturer of the load on specific decoupling
requirements.
The output capacitors are necessary for filtering output
and stabilizing the close loop (see the PWM loop stability).
For powering advanced high-speed processors, it is
required to meet fast load transient requirement. Also high
ESR usually induces ripple that may trigger UV or OV
protections. So High frequency capacitors with low ESR/
ESL capacitors are recommended here.
Linear Regulator Driver
The linear controller of RT9203/A was designed to drive an
external bipolar NPN transistor or a MOSFET. For a
MOSFET, normally DRV need to provide minimum
V
OUT2
+VT+gate-drive voltage to keep V
OUT2
as the set
voltage. When driving MOSFET operating at a 5V power
supply, the gate-drive will be limited at 5V. At this situation,
as shown in Figure 7, a MOSFET with low VT threshold
(VT = 1V) and set Vout2 below 2.5V are suggested. In
V
BOOT
= 12V operation condition, as Figure 8. shown, VCC
is regulated higher than 6V, which providing higher gate-
drive capability for driving the MOSFET, V
OUT2
can be set
as V
OUT2
≤
3.3V.
Figure 8
PWM Loop Stability
The RT9203/A is a voltage mode buck controller designed
for 5V step-down applications. The gain of error amplifier
is fixed at 35dB for simplifying design.
The output amplitude of ramp oscillator is 1.6V, the loop
gain and loop pole/zero are calculated as follows:
The RT9203/A Bode plot is as shown in Figure 9. It is
stable in most of application conditions.
Figure 7
Figure 9
p
p
×
×
A
OUT
V
O
O
5
0.8
DC loop gain G = 35dB
1.75
1
LC filter pole P =
2
LC
Error Amp pole P = 300kHz
1
ESR zero Z =
2 ESR C
Loop
Gain
40
30
20
10
1M
10k
1k
100
100k
V
OUT
= 3.3V
C
= 1500
μ
F(33m
)
L = 2
μ
H
V
OUT
= 1.5V
V
OUT
= 2.5V
V
OUT
= 3.3V
P
O
= 2.9kHz
Z
O
= 3.2kHz
BOOT
VCC
DRV
FBL
RT9203/A
V
CC
= 5V
R4
R3
Max. 5V
Suggest Low
V
T
MOSFET
V
OUT2
< 2.5V
+
R4<1K
BOOT
VCC
DRV
FBL
RT9203/A
6V
R4
R3
Max. 6V
Suggest Low
V
T
MOSFET
V
OUT2
< 3.3V
+
R4<1K
V
BOOT
= 12V
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| RT9203PS | Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller |
| RT9204AGS | Dual Regulators - Standard Buck PWM DC-DC and Linear Controller |
| RT9204APS | Dual Regulators - Standard Buck PWM DC-DC and Linear Controller |
| RT9204GS | Dual Regulators - Standard Buck PWM DC-DC and Linear Controller |
| RT9204PS | Dual Regulators - Standard Buck PWM DC-DC and Linear Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| RT9203PS | 制造商:Richtek 功能描述:DC/DC (IC) |
| RT9204 | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Dual Regulators - Standard Buck PWM DC-DC and Linear Controller |
| RT9204_07 | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Dual Regulators - Standard Buck PWM DC-DC and Linear Controller |
| RT9204AGS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Dual Regulators - Standard Buck PWM DC-DC and Linear Controller |
| RT9204APS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Dual Regulators - Standard Buck PWM DC-DC and Linear Controller |
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