- 您现在的位置：买卖IC网 > PDF目录1849 > MAX8760ETL+T (Maxim Integrated Products)IC CNTRLR QUICK PWM 40-TQFN PDF资料下载
参数资料
| 型号： | MAX8760ETL+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 34/39页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR QUICK PWM 40-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | Quick-PWM™ |
| 应用： | 控制器，6 位 VID AMD 移动式 Turion? |
| 输入电压： | 4 V ~ 28 V |
| 输出数： | 2 |
| 输出电压： | 0.38 V ~ 1.55 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-WFQFN 裸露焊盘 |
| 供应商设备封装： | 40-TQFN-EP（6x6） |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页当前第34页第35页第36页第37页第38页第39页
Dual-Phase, Quick-PWM Controller for AMD
Mobile Turion 64 CPU Core Power Supplies
? ? I
? C f
PD ( N H SWITCHING ) = ( V IN ( MAX ) ) 2 ? RSS SW ? ? LOAD ?
I LOAD = η TOTAL ? I VALLEY ( MAX ) + ?
? ? I
? V
PD ( N H RESISTIVE ) = ? OUT ? ? LOAD ? R DS ( ON )
= η TOTAL I VALLEY ( MAX ) + ? LOAD ( MAX )
?
?
?
cuit longevity.
Power MOSFET Selection
Most of the following MOSFET guidelines focus on the
challenge of obtaining high load-current capability
when using high-voltage (>20V) AC adapters. Low-cur-
rent applications usually require less attention.
The high-side MOSFET (N H ) must be able to dissipate
the resistive losses plus the switching losses at both
V IN(MIN) and V IN(MAX) . Calculate both of these sums.
Ideally, the losses at V IN(MIN) should be roughly equal to
losses at V IN(MAX) , with lower losses in between. If the
losses at V IN(MIN) are significantly higher than the losses
at V IN(MAX) , consider increasing the size of N H (reducing
R DS(ON) but with higher C GATE ). Conversely, if the losses
at V IN(MAX) are significantly higher than the losses at
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. Ensure 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 can occur (see
the MOSFET Gate Driver 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:
? 2
? V IN ? ? η TOTAL ?
where η TOTAL is the total number of phases.
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
voltage, source inductance, and PC board layout
characteristics. The following switching-loss calculation
provides only a very rough estimate and is no substi-
tute for breadboard evaluation, preferably including
verification using a thermocouple mounted on N H :
?
? I GATE ? ? η TOTAL ?
where C RSS is the reverse transfer capacitance of N H
and I GATE is the peak gate-drive source/sink current
(1A typ).
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
PD ( N L RESISTIVE ) = ? 1 ? ? ? ? ? ? R DS ( ON )
? ? V IN ( MAX ) ? ? ? η TOTAL ?
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
circuit to tolerate:
? ? I INDUCTOR ?
? 2 ?
? I LIR ?
2
where I VALLEY(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 of 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
34
______________________________________________________________________________________
相关PDF资料 |
PDF描述 |
|---|---|
| MAX8761ETG+T | IC REG LINEAR LCD 24-TQFN |
| MAX8764ETP+T | IC CNTRL STP DWN HS 20-TQFN |
| MAX8765AETI+ | IC BATT CHARGER MULTICHEM 28TQFN |
| MAX8765ETI+T | IC CHARGER BATTERY 28-TQFN |
| MAX876BCPA | IC VREF SERIES PREC 10V 8-PDIP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8760EVKIT | 功能描述:电流型 PWM 控制器 Evaluation Kit for the MAX8760 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8761ETG+ | 功能描述:LCD 驱动器 Linear-Regulator LCD Panel Power Supply 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 |
| MAX8761ETG+T | 功能描述:LCD 驱动器 Linear-Regulator LCD Panel Power Supply 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 |
| MAX8764EEP | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8764EEP+ | 功能描述:电流型 PWM 控制器 High-Speed Step Down Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
发布紧急采购，3分钟左右您将得到回复。