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参数资料
| 型号： | MAX17409GTI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 29/32页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR NVIDIA CPU 28-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： | 处理器 |
| 电流 - 电源： | 1.5mA |
| 电源电压： | 4.5 V ~ 5.5 V |
| 工作温度： | -40°C ~ 105°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
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1-Phase Quick-PWM GPU Controller
? V OUT ? ?
? ? ( I
) 2 R
V IN ( MAX ) ? ? LOAD DS ( ON )
PD (NH Resistive) = ? OUT ? I LOAD DS (O N)
R
? V IN ?
I LOAD = ? I VALLEY ( MAX ) +
= I VALLEY ( MAX ) + ?
?
?
?
PD (NH Switching) = V IN LOAD SW ?
?
C OSS V IN 2 f SW
N × Q GATE
C BST =
C BST =
= 0 . 24 μF
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 could
occur (see the MOSFET Gate Drivers section).
MOSFET Power Dissipation
Worst-case conduction losses occur in the high-side
MOSFET (N H ) is a function of the duty factor, with the
worst-case power dissipation occurring at the minimum
input voltage:
? V ? 2
O
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 switching losses in a high-side MOSFET
(N H ) is difficult since it must allow for difficult quantify-
ing factors that influence the turn-on and turn-off times.
These factors include the internal gate resistance, gate
charge, threshold voltage, source inductance, and PCB
layout characteristics. The following switching-loss cal-
culation provides only a very rough estimate and is no
substitute for breadboard evaluation, preferably includ-
ing verification using a thermocouple mounted on N H :
? Q G(SW ) ?
I f
? I GATE ?
+
2
where C OSS is the N H MOSFET’s output capacitance,
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).
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:
?
PD (NL Resistive) = ? 1- ?
?
? ? ?
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, the circuit can be overde-
signed to tolerate:
? ? I INDUCTOR ?
?
? 2 ?
? I LOAD(MAX ) 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. 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. 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:
200 mV
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.
______________________________________________________________________________________
29
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1740EUB | 功能描述:转换 - 电压电平 Integrated Circuits (ICs) RoHS:否 制造商:Micrel 类型:CML/LVDS/LVPECL to LVCMOS/LVTTL 传播延迟时间:1.9 ns 电源电流:14 mA 电源电压-最大:3.6 V 电源电压-最小:3 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:MLF-8 |
| MAX1740EUB+ | 功能描述:转换 - 电压电平 SIM/Smart Card Level Translator RoHS:否 制造商:Micrel 类型:CML/LVDS/LVPECL to LVCMOS/LVTTL 传播延迟时间:1.9 ns 电源电流:14 mA 电源电压-最大:3.6 V 电源电压-最小:3 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:MLF-8 |
| MAX1740EUB+T | 功能描述:转换 - 电压电平 SIM/Smart Card Level Translator RoHS:否 制造商:Micrel 类型:CML/LVDS/LVPECL to LVCMOS/LVTTL 传播延迟时间:1.9 ns 电源电流:14 mA 电源电压-最大:3.6 V 电源电压-最小:3 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:MLF-8 |
| MAX1740EUB-T | 功能描述:转换 - 电压电平 RoHS:否 制造商:Micrel 类型:CML/LVDS/LVPECL to LVCMOS/LVTTL 传播延迟时间:1.9 ns 电源电流:14 mA 电源电压-最大:3.6 V 电源电压-最小:3 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:MLF-8 |
| MAX17410EVKIT+ | 功能描述:电源管理IC开发工具 MAX17410 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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