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| 型号： | MAX1875AEEG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 19/22页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 24-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 电压模式 |
| 输出数： | 2 |
| 频率 - 最大： | 660kHz |
| 电源电压： | 4.5 V ~ 23 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 24-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
Dual 180° Out-of-Phase Buck Controllers with
Sequencing/Prebias Startup and POR
MOSFET Selection
The MAX1858A/MAX1875A/MAX1876As ’ step-down
controller drives two external logic-level N-channel
MOSFETs as the circuit switch elements. The key
50
BODE PLOT FOR VOLTAGE-
MODE CONTROLLERS
selection parameters are:
? On-resistance (R DS(ON) )
40
30
f LC
? Maximum drain-to-source voltage (V DS(MAX) )
? Minimum threshold voltage (V TH(MIN) )
20
10
f Z-COMP_A
f ESR
f CO
f SWITCH
? Total gate charge (Q g )
? Reverse transfer capacitance (C RSS )
0
-10
? Power dissipation
All four N-channel MOSFETs must be a logic-level type
-20
-30
f COMP_B
with guaranteed on-resistance specifications at V GS ≥
4.5V. For maximum efficiency, choose a high-side
MOSFET (N H _) that has conduction losses equal to the
-40
0.001
0.01 0.1
FREQUENCY (MHz)
1
P NH ( SWITCHING ) = V IN LOAD SW ? GS GD ?
switching losses at the optimum input voltage. Check to
ensure that the conduction losses at minimum input
voltage do not exceed MOSFET package thermal limits,
or violate the overall thermal budget. Also, check to
ensure that the conduction losses plus switching losses
at the maximum input voltage do not exceed package
ratings or violate the overall thermal budget.
Ensure that the MAX1858A/MAX1875A/MAX1876A DL_
gate drivers can drive N L _. In particular, check that the
dv/dt caused by N H _ turning on does not pull up the N L _
Figure 10. Voltage-Mode Loop Analysis
? Q + Q ?
I f
? I GATE ?
I GATE is the average DH driver-output current capability
determined by:
gate through N L _’s drain-to-gate capacitance. This is the
most frequent cause of cross-conduction problems.
Gate-charge losses are dissipated by the driver and do
I GATE =
2 ( R DS ( ON ) DH + R GATE + R GMOSFET
V L
)
P NH ( CONDUCTION ) = I LOAD 2 R DS ( ON ) NH ? OUT ?
P NL = I LOAD 2 R DS ( ON ) NL ? 1- ? OUT ? ?
not heat the MOSFET. All MOSFETs must be selected
so that their total gate charge is low enough that V L can
power all four drivers without overheating the IC:
P VL = V IN × Q G _ TOTAL × f SW
MOSFET package power dissipation often becomes a
dominant design factor. I 2 R power losses are the great-
est heat contributor for both high-side and low-side
MOSFETs. I 2 R losses are distributed between N H _ and
N L _ according to duty factor as shown in the equations
below. Switching losses affect only the high-side
MOSFET, since the low-side MOSFET is a zero-voltage
switched device when used in the buck topology.
Calculate MOSFET temperature rise according to pack-
age thermal-resistance specifications to ensure that
both MOSFETs are within their maximum junction tem-
perature at high ambient temperature. The worst-case
dissipation for the high-side MOSFET (P NH ) occurs at
both extremes of input voltage, and the worst-case dis-
sipation for the low-side MOSFET (P NL ) occurs at maxi-
mum input voltage.
where R DS(ON)DH is the high-side MOSFET driver’s on-
resistance (5 ? max), R GATE is any series resistance
between DH and BST (Figure 5), and R GMOSFET is the
internal gate resistance of the external MOSFET:
? V ?
? V IN ?
P NH ( TOTAL ) = P NH ( SWITCHING ) + P NH ( CONDUCTION )
? ? V ? ?
? ? V IN ? ?
where P NH(CONDUCTION) is the conduction power loss
in the high-side MOSFET, and P NL is the total low-side
power loss.
To reduce EMI caused by switching noise, add a 0.1μF
ceramic capacitor from the high-side switch drain to
the low-side switch source or add resistors in series
with DL_ and DH_ to increase the MOSFETs’ turn-on
and turn-off times.
______________________________________________________________________________________
19
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1875AEEG+ | 功能描述:电压模式 PWM 控制器 Dual 180 Out PWM Step-Down 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 |
| MAX1875AEEG+T | 功能描述:电压模式 PWM 控制器 Dual 180 Out PWM Step-Down 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 |
| MAX1875AEEG-T | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1875EEG | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1875EEG+ | 功能描述:电压模式 PWM 控制器 Dual 180 Out PWM Step-Down 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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