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参数资料
| 型号： | MAX1830-MAX1831 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | 3A, 1MHz, Low-Voltage, Step-Down Regulators with Synchronous Rectification and Internal Switches |
| 中文描述： | 第3A，1MHz的，低电压，降压型稳压器与同步整流和内部开关 |
| 文件页数： | 8/13页 |
| 文件大小： | 278K |
| 代理商： | MAX1830-MAX1831 |
M
3A, 1MHz, Low-Voltage, Step-Down Regulators with
Synchronous Rectification and Internal Switches
8
_______________________________________________________________________________________
device operates in discontinuous conduction. Current-
sense circuitry monitors the current through the NMOS
synchronous switch, turning it off before the current
reverses. This prevents current from being pulled from
the output filter through the inductor and NMOS switch to
ground. As the device switches between operating
modes, no major shift in circuit behavior occurs.
100% Duty-Cycle Operation
When the input voltage drops near the output voltage,
the duty cycle increases until the PMOS MOSFET is on
continuously. The dropout voltage in 100% duty cycle
is the output current multiplied by the on-resistance of
the internal PMOS switch and parasitic resistance in the
inductor. The PMOS switch remains on continuously as
long as the current limit is not reached.
Internal Digital Soft-Start Circuit
Soft-start allows a gradual increase of the current-limit
level at startup to reduce input-surge currents. The
MAX1830/MAX1831 contain internal digital soft-start cir-
cuits, controlled by a counter, a digital-to-analog con-
verter (DAC), and the current-limit comparator. At
power-on or in shutdown mode, the soft-start counter is
reset to zero. When the MAX1830/MAX1831 are enabled
or powered up, its counter starts counting LX switching
cycles, and the DAC begins incrementing the compari-
son voltage applied to the current-limit comparator. The
DAC ramps up the internal current limit in four 25%
steps, as the count increases to 256 cycles. As a result,
the main output capacitor charges up relatively slowly.
The exact time of the output rise depends on nominal
switching frequency, output capacitance, and the load
current, and is typically 1ms.
Shutdown
Drive
SHDN
to a logic-level low to place the
MAX1830/MAX1831 in low-power shutdown mode and
reduce supply current to less than 1μA. In shutdown, all
circuitry and internal MOSFETs turn off, and the LX
node becomes high impedance. Drive
SHDN
to a
logic-level high or connect to V
CC
for normal operation.
Summing Comparator
Three signals are added together at the input of the
summing comparator (Figure 2): an output-voltage error
signal relative to the reference voltage, an integrated
output-voltage error correction signal, and the sensed
PMOS switch current. The integrated error signal is pro-
vided by a transconductance amplifier with an external
capacitor at COMP. This integrator provides high DC
accuracy without the need for a high-gain amplifier.
Connecting a capacitor at COMP modifies the overall
loop response (see
Integrator Amplifier
).
Table 1. Recommended Component Values (I
OUT
= 3.0A)
0
400
200
800
600
1200
1000
1400
2.6
3.6
4.1
3.1
4.6
5.1
5.6
MAXIMUM RECOMMENDED
OPERATING FREQUENCY vs. INPUT VOLTAGE
M
V
IN
(V)
O
V
OUT
= 1.5V
V
OUT
= 1.8V
V
OUT
= 2.5V
V
OUT
= 3.3V
Figure 3. Maximum Recommended Operating Frequency vs.
Input Voltage
V
IN
(V)
5
5
5
5
5
3.3
3.3
3.3
3.3
V
OUT
(V)
3.3
2.5
1.8
1.5
1.1
2.5
1.8
1.5
1.1
f
PWM
(kHz)
800
865
850
860
625
570
850
860
680
L (μH)
2.2
2.2
2.2
2.2
2.2
1.5
1.5
1.5
1.5
R
TOFF
(k
)
39
56
75
82
130
39
51
62
100
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1830 | Replaced by TMS320BC52 : |
| MAX1831EEE | 3A, 1MHz, Low-Voltage, Step-Down Regulators with Synchronous Rectification and Internal Switches |
| MAX1833ETT30-T | High-Efficiency Step-Up Converters with Reverse Battery Protection |
| MAX1834 | High-Efficiency Step-Up Converters with Reverse Battery Protection |
| MAX1832EUT-T | High-Efficiency Step-Up Converters with Reverse Battery Protection |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1831EEE | 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 |
| MAX1831EEE+ | 功能描述:直流/直流开关调节器 3A 1MHz Step-Down 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 |
| MAX1831EEE+T | 功能描述:直流/直流开关调节器 3A 1MHz Step-Down 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 |
| MAX1831EEE-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 |
| MAX1832EUT | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY STEP-UP CONVERTER - Rail/Tube |
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