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| 型号： | MAX17007AGTI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 32/35页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR QPWM GRAPHICS 28TQFN |
| 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： | 电源 |
| 电流 - 电源： | 1.7mA |
| 电源电压： | 4.5 V ~ 26 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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Dual and Combinable QPWM Graphics
Core Controllers for Notebook Computers
? Q G ( SW ) ?
C OSS V IN ( MAX )2 f SW
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 PCB layout characteristics. 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 :
PD ( NHSwitching ) = V IN ( MAX ) I LOAD f SW ? ?
? I GATE ?
+
2
where C OSS is the N H MOSFET’s output capacitance,
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 MOS-
FET, and I GATE is the peak gate-drive source/sink cur-
rent (2.4A typ).
C BST =
N × Q GATE
200 mV
? V
? ? ( I LOAD DS ( ON )
) 2 R
PD ( NL Re sistive ) = ? 1 ? ?
C BST =
= 0 . 24 μ F
I LOAD = ? I VALLEY ( MAX ) +
? ? I INDUCTOR ?
?
?
?
= I VALLEY ( MAX ) + ?
?
?
?
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:
? ? ?
OUT
? ?
? ? V IN ( MAX ) ? ?
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 “over design” the
circuit to tolerate:
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.
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.
Applications Information
Minimum Input Voltage Requirements
and Dropout Performance
The output-voltage adjustable range for continuous-
conduction operation is restricted by the nonadjustable
minimum off-time one-shot. For best dropout perfor-
mance, use the slower (200kHz) on-time settings. When
working with low input voltages, the duty-factor limit
must be calculated using worst-case values for on- and
off-times. Manufacturing tolerances and internal propa-
gation delays introduce an error to the on-times. This
error is greater at higher frequencies. Also, keep in
mind that transient response performance of buck reg-
ulators operated too close to dropout is poor, and bulk
output capacitance must often be added (see the
Transient Response section (the V SAG equation) in the
Quick-PWM Design Procedure section).
32
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17007BGTI+ | 功能描述:电压模式 PWM 控制器 QPWM Graphics Core Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17007BGTI+T | 制造商:Maxim Integrated Products 功能描述:DUAL AND COMBINABLE QPWM GRAPHICS CORE CONTROLLERS FOR NOTEB - Tape and Reel |
| MAX17007EVKIT+ | 功能描述:电源管理IC开发工具 QPWM Graphics Core Controller 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 |
| MAX17007GTI+ | 功能描述:电压模式 PWM 控制器 QPWM Graphics Core Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX17007GTI+T | 功能描述:电压模式 PWM 控制器 QPWM Graphics Core Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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