参数资料
| 型号： | MAX1945REUI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 11/19页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 6A 28TSSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 两者兼有 |
| 输出数： | 1 |
| 输出电压： | 1.8V，2.5V，可调 |
| 输入电压： | 2.6 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 400kHz ~ 1.2MHz |
| 电流 - 输出： | 6A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SOIC（0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 28-TSSOP 裸露焊盘 |
1MHz, 1% Accurate, 6A Internal Switch
Step-Down Regulators
Pin Description (continued)
PIN
19, 21, 23,
25
27
28
NAME
PGND
CTL1
CTL2
EP
FUNCTION
Power Ground. Connect all PGND together close to the device. Star connect GND to PGND (see the PC
Board Layout Considerations section).
Output Margining Control Inputs. When CTL1 = CTL2 = GND, the regulator is off. When CTL1 = CTL2 =
V CC , the regulator runs at nominal output voltage. When CTL1 = V CC and CTL2 = GND, the output is set
to the margin-low output (-4% or -9%). When CTL1 = GND and CTL2 = V CC , the output is set to the
margin-high output (+4% or +9%).
Exposed Pad. Connect to PGND to improve power dissipation.
Detailed Description
The MAX1945R/MAX1945S high-efficiency PWM
switching regulators deliver up to 6A of output current.
The devices operate at a selectable fixed frequency
(500kHz or 1MHz) or can be synchronized to an exter-
nal frequency (400kHz to 1.2MHz). The devices oper-
ate from a 2.6V to 5.5V input supply voltage and have a
selectable output voltage of 1.8V or 2.5V, or an
adjustable output voltage from 0.8V to 85% of the input
voltage, making the MAX1945R/MAX1945S ideal for on-
board post-regulation applications. The high switching
frequency allows the use of small external components.
Internal synchronous rectifiers improve efficiency and
eliminate the typical Schottky freewheeling diode. Total
output error over load, line, and temperature is less
than ±1%.
Controller Function
The MAX1945R/MAX1945S step-down converters use a
PWM current-mode control scheme. A PWM comparator
compares the integrated voltage-feedback signal
against the sum of the amplified current-sense signal
and the slope-compensation ramp. At each rising edge
of the internal clock, the internal high-side MOSFET
turns on until the PWM comparator trips. During this on-
time, current ramps up through the inductor, sourcing
current to the output and storing energy in the inductor.
The current-mode feedback system regulates the peak
inductor current as a function of the output voltage
error signal. Because the average inductor current is
nearly the same as the peak inductor current (<30%
ripple current), the circuit acts as a switch-mode
transconductance amplifier.
To preserve inner-loop stability and eliminate inductor
staircasing, a slope-compensation ramp is summed into
the main PWM comparator. During the off-cycle, the
internal high-side N-channel MOSFET turns off, and the
internal low-side N-channel turns on. The inductor releas-
es the stored energy as its current ramps down while still
providing current to the output. The output capacitor
stores charge when the inductor current exceeds the
load current and discharges when the inductor current is
lower, smoothing the voltage across the load. During an
overload condition, when the inductor current exceeds
the current limit (see the Current Limit section), the high-
side MOSFET does not turn on at the rising edge of the
clock, and the low-side MOSFET remains on to let the
inductor current ramp down.
Current Sense
An internal current-sense amplifier produces a current
signal proportional to the voltage generated by the high-
side MOSFET on-resistance and the inductor current
(R DS(ON) ? I LX ). The amplified current-sense signal and
the internal slope-compensation signal sum together at
the comparator inverting input. The PWM comparator
turns off the internal high-side MOSFET when this sum
exceeds the COMP voltage from the error amplifier.
Current Limit
The internal high-side MOSFET has a current limit of
8A (min). If the current flowing out of LX exceeds this limit,
the high-side MOSFET turns off and the synchronous rec-
tifier turns on. This lowers the duty cycle and causes the
output voltage to droop until the current limit is no longer
exceeded. The minimum duty cycle is limited to 10%. A
synchronous rectifier current limit of 2A minimum protects
the device from current flowing into LX.
When the negative current limit is exceeded, the device
turns off the synchronous rectifier, forcing the inductor
current to flow through the high-side MOSFET body
diode and back to the input, until the beginning of the
next cycle, or until the inductor current drops to zero.
The MAX1945R/MAX1945S use a pulse-skip mode to
prevent overheating during short-circuit output condi-
tions. The device enters pulse-skip mode when the FB
voltage drops below 300mV, limiting the current and
reducing power dissipation. Normal operation resumes
upon removal of the short-circuit condition.
______________________________________________________________________________________
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1945SEUI | 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 |
| MAX1945SEUI+ | 功能描述:直流/直流开关调节器 1MHz 1% 6A Step-Down PWM 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 |
| MAX1945SEUI+T | 功能描述:直流/直流开关调节器 1MHz 1% 6A Step-Down PWM 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 |
| MAX1945SEUI-T | 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 |
| MAX1946ETA | 制造商:Maxim Integrated Products 功能描述:SINGLE USB SWITCH WITH AUTORESET AND FAULT BL - Rail/Tube |
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