- 您现在的位置：买卖IC网 > Sheet目录694 > MAX17009GTL+ (Maxim Integrated)IC CTLR VIDEO SERIAL DUAL 40TQFN
AMD Mobile Serial VID Dual-Phase
Fixed-Frequency Controller
? V IN ( MAX ) ? ? ? ? η TOTAL ?
PD ( NL Re sistive ) = ? 1 ? ? ? ? ? ? R DS ( ON )
V IN(MIN) , consider reducing the size of N H (increasing
R DS(ON) to lower C GATE ). If V IN does not vary over a
wide range, the minimum power dissipation occurs
where the resistive losses equal the switching losses.
Choose a low-side MOSFET that has the lowest possible
on-resistance (R DS(ON) ), comes in a moderate-sized
package (i.e., one or two 8-pin SOs, DPAK, or D 2 PAK),
and is reasonably priced. Make sure that the DL gate
driver can supply sufficient current to support the gate
charge and the current injected into the parasitic gate-
to-drain capacitor caused by the high-side MOSFET
turning on; otherwise, cross-conduction problems may
occur (see the MOSFET Gate Drivers section).
MOSFET Power Dissipation
Worst-case conduction losses occur at the duty-factor
extremes. For the high-side MOSFET (N H ), the worst-
case power dissipation due to resistance occurs at the
minimum input voltage:
Switching losses in the high-side MOSFET can become
an insidious heat problem when maximum AC adapter
voltages are applied, due to the squared term in the C
x V IN 2 x f SW switching-loss equation. If the high-side
MOSFET chosen for adequate R DS(ON) at low-battery
voltages becomes extraordinarily hot when biased from
V IN(MAX) , consider choosing another MOSFET with
lower parasitic capacitance.
For the low-side MOSFET (N L ), the worst-case power
dissipation always occurs at maximum input voltage:
? ? V OUT ? ? ? I LOAD ? 2
? ?
The worst case for MOSFET power dissipation occurs
under heavy overloads that are greater than
I LOAD(MAX) but are not quite high enough to exceed
the current limit and cause the fault latch to trip. To pro-
tect against this possibility, you can “overdesign” the
PD ( NH Re sistive ) = ? OUT ? I LOAD 2 R DS ( ON )
? V ?
? V IN ?
circuit to tolerate:
I LOAD ( MAX ) = I PEAK ( MAX ) ?
Δ I INDUCTOR
2
= I PEAK ( MAX ) ? ?
?
?
?
PD ( NHSwitching ) = ( V IN ( MAX ) ) ? RSS SW ? I LOAD
where I LOAD is the per-phase current.
Generally, a small high-side MOSFET is desired to
reduce switching losses at high input voltages.
However, the R DS(ON) required to stay within package
power dissipation often limits how small the MOSFET
can be. Again, the optimum occurs when the switching
losses equal the conduction (R DS(ON) ) losses. High-
side switching losses do not usually become an issue
until the input is greater than approximately 15V.
Calculating the power dissipation in high-side MOSFET
(N H ) due to switching losses is difficult since it must
allow for difficult quantifying factors that influence the
turn-on and turn-off times. These factors include the
internal gate resistance, gate charge, threshold volt-
age, source inductance, and PCB layout characteris-
tics. The following switching-loss calculation provides
only a very rough estimate and is no substitute for
breadboard evaluation, preferably including verification
using a thermocouple mounted on N H :
2 ? C f ?
? I GATE ?
where C RSS is the reverse transfer capacitance of N H
and I GATE is the peak gate-drive source/sink current
(1A typ), and I LOAD is the per-phase current.
? I LOAD ( MAX ) LIR ?
2
where I PEAK(MAX) is the maximum valley current
allowed by the current-limit circuit, including threshold
tolerance and on-resistance variation. The MOSFETs
must have a good-size heatsink to handle the overload
power dissipation.
Choose a Schottky diode (D L ) with a forward voltage
low enough to prevent the low-side MOSFET body
diode from turning on during the dead time. As a gen-
eral rule, select a diode with a DC current rating equal
to 1/3 the load current per phase. This diode is optional
and can be removed if efficiency is not critical.
Boost Capacitors
The boost capacitors (C BST ) must be selected large
enough to handle the gate-charging requirements of
the high-side MOSFETs. Typically, 0.1μF ceramic
capacitors work well for low-power applications driving
medium-sized MOSFETs. However, high-current appli-
cations driving large, high-side MOSFETs require boost
capacitors larger than 0.1μF. For these applications,
select the boost capacitors to avoid discharging the
capacitor more than 200mV while charging the high-
side MOSFETs’ gates:
C BST =
N × Q GATE
200 mV
38
______________________________________________________________________________________
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
MAX17410GTM+
IC CTLR QPWM 2PH FOR IMV 48TQFN
MC2711H
SWITCH BUSHING PLUNGER W/SEAL
MC2711
SWITCH BUSHING MOUNT PLUNGER
MC7711
SWITCH BUSHING MOUNT PLUNGER
MCA7711
SWITCH BUSHING MOUNT PLUNGER
MCD2711
SWITCH BUSHING MOUNT PLUNGER
MCD7711
SWITCH BUSHING MOUNT PLUNGER
MCZ2010AH900
CHOKE COMMON MODE 90 OHM SMD
相关代理商/技术参数
MAX17009GTL+T
功能描述:其他电源管理 AMD Dual-Phase CPU Controller RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel
MAX1700EEE
功能描述:直流/直流开关转换器 1-3 Cell 1A Step-Up DC/DC Converters RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT
MAX1700EEE+
功能描述:直流/直流开关转换器 1-3 Cell 1A Step-Up DC/DC Converters
RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT
MAX1700EEE+T
功能描述:直流/直流开关转换器 1-3 Cell 1A Step-Up DC/DC Converters RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT
MAX1700EEE-T
功能描述:直流/直流开关转换器 1-3 Cell 1A Step-Up DC/DC Converters RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT
MAX17010AETL+
功能描述:LCD 驱动器 Internal-Switch Boost Regulator RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube
MAX17010AETL+T
功能描述:LCD 驱动器 Internal-Switch Boost Regulator RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube
MAX17010ETL+
功能描述:LCD 驱动器 Internal-Switch Boost Regulator RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube