- 您现在的位置：买卖IC网 > PDF目录1839 > MAX17024ETD+T (Maxim Integrated Products)IC REG CTRLR DIVIDER PWM 14TDFN PDF资料下载
参数资料
| 型号： | MAX17024ETD+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 21/25页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR DIVIDER PWM 14TDFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | Quick-PWM™ |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 600kHz |
| 电源电压： | 2 V ~ 26 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 是 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | 0°C ~ 85°C |
| 封装/外壳： | 14-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
Single Quick-PWM Step-Down
Controller with Dynamic REFIN
? Q G ( SW ) ?
PD ( N H IN ( MAX ) I LOAD SW ?
C BST =
rough estimate and is no substitute for breadboard
evaluation, preferably including verification using a
thermocouple mounted on N H :
Switching ) = V f ? +
? I GA T E ?
C OSS V IN ( MAX )2 f SW
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 MOS-
FET, and I GATE is the peak gate-drive source/sink cur-
rent (2.4A 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.
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 applica-
tions, select the boost capacitors to avoid discharging
the capacitor more than 200mV while charging the
high-side MOSFETs’ gates:
N × Q GATE
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:
For the low-side MOSFET (N L ), the worst-case power
dissipation always occurs at maximum input voltage:
C BST =
2 × 24nC
200 mV
= 0 . 24 μ F
? ( I LOAD ) R DS ( ON )
V IN ( MAX ) ? ? ? ?
PD ( N L Re sistive ) = ? 1 ? ?
? ?
I LOAD = I VALLEY ( MAX ) +
= I VALLEY ( MAX ) + ?
?
?
?
? ? V OUT ? ? 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
circuit to tolerate:
? I L
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.
Selecting the closest standard value, this example
requires a 0.22μF ceramic capacitor.
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 V SAG
equation in the Transient Response section).
The absolute point of dropout is when the inductor cur-
rent ramps down during the minimum off-time ( ? I DOWN )
as much as it ramps up during the on-time ( ? I UP ). The
ratio h = ? I UP / ? I DOWN is an indicator of the ability to
slew the inductor current higher in response to
increased load, and must always be greater than 1. As
h approaches 1, the absolute minimum dropout point,
the inductor current cannot increase as much during
each switching cycle and V SAG greatly increases
unless additional output capacitance is used.
______________________________________________________________________________________
21
相关PDF资料 |
PDF描述 |
|---|---|
| MAX17028GTJ+ | IC PWM CTRL IMVP-6.5/GMCH 32TQFN |
| MAX17030GTL+ | IC CTRLR VID QUICK-PWM 40-TQFN |
| MAX1703ESE | IC REG BOOST SYNC 5V/ADJ 16SOIC |
| MAX17041G+T | IC 2-WIRE FG W/MODEL GAUGE |
| MAX17044G+T | IC FUEL GAUGE LI-ION 8-TDFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17024EVKIT+ | 制造商:Maxim Integrated Products 功能描述:MAX17024 EVAL KIT - Boxed Product (Development Kits) |
| MAX17026 | 功能描述:直流/直流开关调节器 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX17028GTJ+ | 功能描述:电压模式 PWM 控制器 Intel GMCH Single Phase PWM 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 |
| MAX17028GTJ+T | 功能描述:电压模式 PWM 控制器 Intel GMCH Single Phase PWM 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 |
| MAX1702BEGX | 功能描述:PMIC 解决方案 RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
发布紧急采购，3分钟左右您将得到回复。