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参数资料
| 型号： | MAX5951ETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/25页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 32-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 88% |
| 电源电压： | 4.5 V ~ 16 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： | 32-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
12V/5V Input Buck PWM Controller
Error Amplifier
The output of the internal error amplifier (COMP) is
available for frequency compensation (see the
Compensation Design Guidelines section). The invert-
ing input is FB; the output is COMP. The error amplifier
has an 80dB open-loop gain and a 2.5MHz GBW prod-
uct. See the Typical Operating Characteristics for the
Open-Loop Gain and Phase vs. Frequency graph.
PWM Comparator
An internal ramp is compared against the output of the
error amplifier to generate the PWM signal. The ampli-
tude of the ramp, V RAMP, is 1.8V.
Output Short-Circuit Protection
(Hiccup Mode)
The current-limit circuit employs a lossless valley cur-
rent-limiting algorithm that uses the MOSFET’s on-resis-
tance as the current-sensing element. Once the
high-side MOSFET turns off, the voltage across the low-
side MOSFET is monitored. If the voltage across the
low-side MOSFET (R DS(ON) x I INDUCTOR ) does not
exceed the current-limit threshold, the high-side MOS-
FET turns on normally at the start of the next cycle. If
count of N CL is cleared (see Figure 2). Hiccup mode
protects against continuous output short circuit.
Thermal-Overload Protection
The MAX5951 features an integrated thermal-overload
protection with temperature hysteresis. Thermal-over-
load protection limits the total power dissipation in the
device and protects it in the event of an extended ther-
mal fault condition. When the die temperature exceeds
+135°C, an internal thermal sensor shuts down the
device, turning off the power MOSFETs and allowing
the die to cool. After the die temperature falls by
+15°C, the part restarts with a soft-start sequence.
PWM Controller Design
Procedures
Setting the Undervoltage Lockout
Connect an external resistive divider from IN to PUVLO
to AGND to override the internal PWM UVLO divider.
The rising threshold at PUVLO is set to 1.220V with
120mV hysteresis. First select the PUVLO to AGND
resistor (R2), then calculate the resistor from IN to
PUVLO (R1) using the following equation:
R 1 = R 2 × ?
? 1 ?
the voltage across the low-side MOSFET exceeds the
current-limit threshold just before the beginning of a
new PWM cycle, the controller skips that cycle. During
severe overload or short-circuit conditions, the switch-
?
?
V IN
V PUVLO
?
?
ing frequency of the device appears to decrease
because the on-time of the low-side MOSFET extends
beyond a clock cycle.
If the current-limit threshold is exceeded for eight cumu-
lative clock cycles (N CL ), the device shuts down (both
DH and DL are pulled low) for 512 clock cycles (hiccup
timeout) and restarts with a soft-start sequence. If three
consecutive cycles pass without a current-limit event, the
where V IN is the input voltage at which the converter
needs to turn on, V PUVLO = 1.220V, and R2 is chosen
to be less than 20k ? . See Figure 3.
Leave PUVLO unconnected for the default PWM UVLO
threshold. In this case, an internal voltage-divider moni-
tors the supply voltage at IN and allows startup when
IN rises above 7V (typ).
IN
CURRENT LIMIT
IN
COUNT OF 8
N CL
INITIATE HICCUP
TIMEOUT
N HT
R1
CLR
PUVLO
IN
COUNT OF 3
N CLR
R2
CLR
Figure 2. Hiccup Block Diagram
Figure 3. External PWM UVLO Divider
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX5952AEAX+ | 功能描述:热插拔功率分布 Quad PSE Controller for POE RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MAX5952AEAX+CK8 | 功能描述:热插拔功率分布 Quad PSE Controller for POE RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MAX5952AEAX+T | 功能描述:热插拔功率分布 Quad PSE Controller for POE RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MAX5952AEVCMAXQU | 功能描述:热插拔功率分布 Evaluation Kit/Evaluation System for the MAX5952A RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MAX5952AEVKIT | 功能描述:电源管理IC开发工具 Evaluation Kit/Evaluation System for the MAX5952A 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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