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| 型号： | MAX17528GTJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 39/41页 |
| 文件大小： | 0K |
| 描述： | IC PWM CTRLR STP-DWN 32TQFN-EP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 系列： | Quick-PWM™ |
| 应用： | 控制器，Intel IMVP-6.5? GMCH |
| 输入电压： | 4.5 V ~ 5.5 V |
| 输出数： | 1 |
| 输出电压： | 0.01 V ~ 1.5 V |
| 工作温度： | -40°C ~ 105°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 管件 |
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1-Phase Quick-PWM
Intel IMVP-6.5/GMCH Controllers
PD ( NH Re sistive ) = ? OUT ? ( I LOAD ) R DS ( ON )
? = I VALLEY ( MAX )
I LOAD = ? I VALLEY ( MAX ) +
? Q G ( SW ) ?
C OSS IN SW
V f
PD ( NHSwitching ) = V IN ( MAX ) I LOAD SW ? ?+
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:
? V ? 2
? V IN ?
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 complicated 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
f
? I GATE ? 2
where C OSS is the N H MOSFET’s output capacitance,
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 “over design” the
circuit to tolerate:
? ? I INDUCTOR ?
? 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. Select a
diode that can handle the load current during the dead
times. This diode is optional and can be removed if effi-
ciency 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:
Q G(SW) is the charge needed to turn on the N H MOSFET,
and I GATE is the peak gate-drive source/sink current
(2.2A typ).
C BST =
N × Q GATE
200 mV
? ? ( I LOAD DS ( ON )
) 2 R
PD ( NL Re sistive ) = ? 1 ? ?
C BST =
= 0 . 24 μF
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
? ?
? ? V IN ( MAX ) ? ?
The worst case for MOSFET power dissipation occurs
under heavy overloads that are greater than
where N is the number of high-side MOSFETs used for
one regulator, and Q GATE is the gate charge specified
in the MOSFET’s data sheet. For example, assume (2)
IRF7811W n-channel MOSFETs are used on the high
side. According to the manufacturer’s data sheet, a sin-
gle IRF7811W has a maximum gate charge of 24nC
(V GS = 5V). Using the above equation, the required
boost capacitance would be:
2 × 24nC
200 mV
Selecting the closest standard value, this example
requires a 0.22μF ceramic capacitor.
______________________________________________________________________________________
39
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17528GTJ+ | 功能描述:电流型 PWM 控制器 1-Phase Quick-PWM 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 |
| MAX17528GTJ+T | 功能描述:电流型 PWM 控制器 1-Phase Quick-PWM 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 |
| MAX17535ETG+ | 功能描述:电池管理 High Frequency SMBus Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX17535ETG+T | 功能描述:电池管理 High Frequency SMBus Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX17535EVKIT+ | 功能描述:电池管理 EVKIT RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
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