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參數(shù)資料
| 型號(hào)： | RT9202BGS |
| 廠商： | Richtek Technology Corporation |
| 英文描述： | Single Synchronous Buck PWM DC-DC Controller |
| 中文描述： | 單同步降壓PWM DC - DC控制器 |
| 文件頁(yè)數(shù)： | 10/14頁(yè) |
| 文件大?。?/td> | 209K |
| 代理商： | RT9202BGS |
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RT9202B
10
DS9202B-03 March 2007
www.richtek.com
Both V
SET
and V
DS
are referenced to V
IN
and a small
capacitor across R
OCSET
helps V
OCSET
tracking the
variations of V
IN
due to MOSFET switching. The over-
current function will be tripped at a peak inductor current
(I
PEAK
) determined by :
The OC trip point varies with MOSFET's R
DS(ON)
temperature variations. The temperature coefficient of
I
OCSET
is 2500ppm that is used to compensate R
DS(ON)
temperature variations. To avoid over-current tripping in
the normal operating load range, determine the R
OCSET
resistor value from the equation above with:
1.The maximum R
SD(ON)
at the highest junction
temperature
2.The minimum I
OCSET
from the characteristics
3.Determine I
PEAK
for I
PEAK
> I
OUT(MAX)
+ (
I)/2
where
I is the output inductor ripple current.
Under Voltage and Over Voltage Protection
The voltage at FB pin is monitored and protected against
OC (over current), UV (under voltage), and OV (over
voltage). The UV threshold is 0.5V and OV-threshold is
1.0V. Both UV/OV detection have 30
μ
s triggered delay.
When OC or UV trigged, a hiccup re-start sequence will
be initialized, as shown in Figure 4. Only 3 times of trigger
are allowed to latch off. Hiccup is disabled during soft-
start interval.
Shutdown
Pulling low the OCSET pin can shutdown the RT9202B
PWM controller as shown in typical application circuit.
Inductor Selection
The RT9202B was designed for V
IN
= 5V, step-down
application mainly. Figure 5 shows the typical topology
and waveforms of step-down converter.
The ripple current of inductor can be calculated as follows:
IL
RIPPLE
= (5V - V
OUT
)/L
×
T
ON
Because operation frequency is fixed at 300kHz,
T
ON
= 3.33
×
V
OUT
/5V
The V
OUT
ripple is
V
OUT RIPPLE
= IL
RIPPLE
×
ESR
ESR is output capacitor equivalent series resistor
Table 1 shows the ripple voltage of V
OUT
: VIN = 5V
GATE
CONTROL
+
-
PWM
OC
DRIVE
VCC
OCSET
R
OCSET
V
SET+
V
IN
= +5V
V
DS+
i
D
UGATE
PHASE
I
OCSET
20uF
OVER-CURRENT TRIP:
V
DS
> V
SET
×
D
DS(ON)
i
R
> I
×
OCSET
OCSET
R
V
OCSET
= V
IN
- V
SET
V
PHASE
= V
IN
- V
DS
0A
0V
2V
4V
I
S
I
T1
T2
T3
TIME
COUNT = 1 COUNT = 2 COUNT = 3
OVERLOAD
APPLIED
T0
Figure 3
Figure 4
DS(ON)
OCSET
OCSET
I
=
PEAK
I
R
R
×
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| RT9202BPS | Single Synchronous Buck PWM DC-DC Controller |
| RT9202GS | Single Synchronous Buck PWM DC-DC Controller |
| RT9202PS | Single Synchronous Buck PWM DC-DC Controller |
| RT9203AGS | Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller |
| RT9203APS | Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| RT9202BPS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Single Synchronous Buck PWM DC-DC Controller |
| RT9202CS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:SINGLE SYNCHRONOUS BUCK PWM DC-DC CONTROLLER |
| RT9202GS | 制造商:Richtek Technology Corporation 功能描述: |
| RT9202PS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Single Synchronous Buck PWM DC-DC Controller |
| RT9203 | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller |
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