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參數(shù)資料
| 型號： | RT9241B |
| 文件頁數(shù)： | 10/18頁 |
| 文件大?。?/td> | 333K |
| 代理商： | RT9241B |
RT9241A/B
www.richtek.com
10
DS9241AB-01 October 2002
Operation
RT9241A/B is a two-phase DC/DC controller that
precisely regulates CPU core voltage and balances
the current of different power channels. The converter
consists of RT9241A/B and its companion MOSFET
driver provide high quality CPU power and all
protection function to meet the requirement of modern
VRM.
Voltage control
The reference of V
CORE
is provided by a 5-bit DAC of
VRM9.0 specification. Control loop consists of error
amplifier, two-phase pulse width modulator, driver and
power components. Like conventional voltage mode
PWM controller, the output voltage is locked at the
V
REF
of error amplifier and the error signal is used as
the control signal V
C
of pulse width modulator. The
PWM signals of different channels are generated by
comparison of EA output and split-phase saw-tooth
wave. Power stage transforms V
IN
to output by PWM
signal on-time ratio.
Current balance
RT9241A/B senses the current of low side MOSFET
in each synchronous rectifier when it is conducting for
channel current balance and droop tuning. The
differential sensing GM amplifier converts the voltage
on the sense component (can be a sense resistor or
the R
DS(ON)
of the low side MOSFET) to current
signal into internal balance circuit. The current
balance circuit sums and averages the current signals
then produces the balancing signals injected to pulse
width modulator. If the current of some power channel
is greater than average, the balancing signal reduces
the output pulse width to keep the balance.
Load droop
The sensed power channel current signals regulate
the reference of DAC to form a output voltage droop
proportional to the load current. The droop or so call
“active voltage positioning” can reduce the output
voltage ripple at load transient and the LC filter size.
Fault detection
The chip detects V
CORE
for over voltage and power
good detection. The “hiccup mode” operation of over
current protection is adopted to reduce the short
circuit current. The in-rush current at the start up is
suppressed by the soft start circuit through clamping
the pulse width and output voltage.
Application Circuit Setting
MOSFET driver detection and converter start up
RT9241A/B interface with companion MOSFET driver
(like RT9600 or HIP660X series) for correct converter
initialization. The tri-phase PWM output (high, low,
high impedance) pins sense the interface voltage at
IC POR acts (both V
DD
and V
DVD
trip). The channel is
enabled if the pin voltage is 1.2V less than V
DD
.
Please tie the both PWM output to driver input for
correct converter start-up.
Current sensing setting
RT9241A/B senses the current of low side MOSFET
in each synchronous rectifier when it is conducting for
channel current balance and droop tuning. The
differential sensing GM amplifier converts the voltage
on the sense component (can be a sense resistor or
the R
DS(ON)
of the low side MOSFET) to current
signal into internal circuit (see Fig.1).
Fig.1 Current Sense Circuit
Sample & Hold
GM
To Current Balance
To Droop Tune
To Over Current Detection
2/3 I
X
2/3 I
X
2/3 I
X
I
X
+
_
I
BP
I
BN
R
SP
R
SN
R
S
I
L
ISP
X
ISN
X
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| RT9241A | |
| RT9261 | Step-up DC/DC Converter |
| RT9261A | Step-up DC/DC Converter |
| RT9266 | Step-up DC/DC Converter |
| RT9266B | Step-up DC/DC Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| RT9241BGS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Two-Phase DC/DC Controller for CPU Core Power Supply |
| RT9241BPS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Two-Phase DC/DC Controller for CPU Core Power Supply |
| RT9241CS | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Two-Phase DC/DC Controller for CPU Core Power Supply |
| RT9243 | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Multi-Phase PWM Controller for CPU Core Power Supply |
| RT9243GS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Multi-Phase PWM Controller for CPU Core Power Supply |
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