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參數(shù)資料
| 型號(hào)： | RT9641B |
| 英文描述： | Triple Linear Regulator Controller Support ACPI Control Interface |
| 中文描述： | 三線性穩(wěn)壓控制器支持ACPI控制接口 |
| 文件頁(yè)數(shù)： | 10/11頁(yè) |
| 文件大?。?/td> | 326K |
| 代理商： | RT9641B |
10
RT9641A/B
capacitors.
The RT9641A/B typically requires one P-channel or PNP
transistor and two N-channel power MOSFETs and two
bipolar NPN transistors.
One general requirement for selection of transistors for all
the linear regulators/switching elements is package
selection for efficient removal of heat. The power dissipated
in a linear regulator/switching element is:
P
LINEAR
= I
O
x (V
IN
- V
OUT
)
Select a package and heatsink that maintains the junction
temperature below the rating with the maximum expected
ambient temperature.
Q1
The active element on the 2.5V/3.3V (2.6V/3.43V) V
MEM
output has different requirements for each the two voltage
settings. In 2.5V systems utilizing RDRAM (or voltage-
compatible) memory, Q1 had better to be a bipolar NPN
capable of conducting the maximum required output
current and it must have a minimum current gain (h
fe
) of
100~150 at this current and 0.7V V
CE
. In such systems,
the 2.5V(2.6V) output is regulated from the ATX 3.3V output
while in an active state. In 3.3V systems (SDRAM or
compatible) Q1 is suggested to use an N-channel
MOSFET, then the MOSFET serves like a switch when it
is connected to ATX3.3V during active states (S0, S1).
The main criteria for the selection of this transistor is output
voltage budgeting. The maximum R
DS(ON)
allowed at
highest junction temperature can be expressed with the
following equation:
R
DS(ON)
MAX
= (V
IN MIN
V
OUT MIN
)/ I
OUT MAX
, where
V
IN MIN
:minimum input voltage
V
OUT
MIN
: minimum output voltage allowed.
I
OUT
MAX
: maximum output current
The gate bias available for this MOEFET is approximately
6V, so the logic level MOSFET is prefered. The
3.3V(3.43V) V
MEM
power also can be regulated from ATX
5V in order to have high quality V
MEM
, in such a
configuration, either MOSFET or NPN transistors can be
Transistor Selection/Considerations
used. While the heat dissipation should be carefully
handled.
Q4
If a P-chanel MOSFET is used to switch the 5VSB output
of the ATX supply into the 5V
DUAL
output during S3 and
S4/S5 states (as dictated by EN5VDL status), then, similar
to the situation where Q1 is a MOSFET, the selection
criteria of this device is also proper voltage budgeting.
The maximum r
DS (ON)
, however, has to be achieved with
only 4.5V of V
GS
, so a logic level MOSFET needs to be
selected. If a PNP device is chosen to perform this function,
it has to have a low saturation voltage while providing the
maximum sleep-state current and have current gain
sufficiently high to be saturated using the minimum drive
current (typically 20mA). A 100
~ 200
resistor is
recommended to be inserted between the 5VDLSB pin
and Base node of the PNP transistor for limiting the base
current.
Q3, Q5
The two N-channel MOSFETs are used to switch the 3.3V
and 5V inputs provided by the ATX supply into the 3.3V
DUAL
and 5V
DUAL
outputs, respectively, while in active (S0, S1)
state. Similar R
DS(ON)
criteria apply in these cases as well,
unlike the PMOS, however, these NMOS transistors get
the benefit of an increased V
GS
drive (approximately 8V
and 7V respectively).
Q2
The NPN transistor used as sleep-state pass element on
the 3.3V
DUAL
output must have a minimum current gain of
100 at V
CE
= 1.5V and I
CE
= 500mA throughout the in-
circuit operating temperature range.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| RT9702 | Power Management/Switchers |
| RT9702A | Power Management/Switchers |
| RT9801A | Power Management/Voltage Dector |
| RT9801B | Power Management/Voltage Dector |
| RT9802A | Power Management/Voltage Dector |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| RT9641BCS2 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:TRIPLE LINEAR REGULATOR CONTROLLER SUPPORT |
| RT9641BGS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Triple Linear Regulator Controller Support ACPI Control Interface |
| RT9641BPS | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:Triple Linear Regulator Controller Support ACPI Control Interface |
| RT9643 | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:5 Channel ACPI Regulator with Step-Down DC/DC Controller |
| RT9643_11 | 制造商:RICHTEK 制造商全稱:Richtek Technology Corporation 功能描述:5 Channel ACPI Regulator with Step-Down DC/DC Controller |
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