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| 型号： | MAX1845ETX+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 11/27页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 36-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 540kHz |
| 电源电压： | 4.5 V ~ 5.5 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： | 36-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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Dual, High-Efficiency, Step-Down
Controller with Accurate Current Limit
time is determined solely by a one-shot whose pulse
width is inversely proportional to input voltage and
directly proportional to output voltage. Another one-shot
sets a minimum off-time (400ns typ). The on-time one-
shot is triggered if the error comparator is low, the low-
side switch current is below the current-limit threshold,
and the minimum off-time one-shot has timed out
(Table 3).
On-Time One-Shot (TON)
The heart of the PWM core is the one-shot that sets the
high-side switch on-time for both controllers. This fast,
low-jitter, adjustable one-shot includes circuitry that
varies the on-time in response to battery and output
voltage. The high-side switch on-time is inversely pro-
portional to the battery voltage as measured by the V+
input, and proportional to the output voltage. This algo-
rithm results in a nearly constant switching frequency
despite the lack of a fixed-frequency clock generator.
The benefits of a constant switching frequency are
twofold: First, the frequency can be selected to avoid
noise-sensitive regions such as the 455kHz IF band;
second, the inductor ripple-current operating point
V DD = 5V
BIAS SUPPLY
remains relatively constant, resulting in easy design
methodology and predictable output voltage ripple.
The on-times for side 1 are set 35% higher than the on-
times for side 2. This is done to prevent audio-frequen-
cy “beating ” between the two sides, which switch
asynchronously for each side. The on-time is given by:
On-Time = K (V OUT + 0.075V) / V IN
where K is set by the TON pin-strap connection (Table
4), and 0.075V is an approximation to accommodate
for the expected drop across the low-side MOSFET
switch. One-shot timing error increases for the shorter
on-time settings due to fixed propagation delays; it is
approximately ±12.5% at higher frequencies and ±10%
at lower frequencies. This translates to reduced switch-
ing-frequency accuracy at higher frequencies (Table
4). Switching frequency increases as a function of load
current due to the increasing drop across the low-side
MOSFET, which causes a faster inductor-current dis-
charge ramp. The on-times guaranteed in the Electrical
Characteristics tables are influenced by switching
delays in the external high-side power MOSFET.
C9
4.7 μ F
C8
1 μ F
D3
CMPSH-3A
V IN
C11
1 μ F
R1
20 Ω
21
9
22
3
13
V DD
UVP
V CC
ILIM1
ILIM2
4
V+
ON1
ON2
OVP
11
12
8
7V TO 24V
C2
ON/OFF
CONTROLS
MAX1845EEI
2 ? 10 μ F
C1
3 ? 10 μ F
25
BST1
BST2
19
OUTPUT1
1.8V, 8A
C3
3 ? 470 μ F
L1
2.2 μ H
D1
Q1
Q2
C5
0.1 μ F
26
27
24
DH1
LX1
DL1
DH2
LX2
DL2
18
17
20
C6
0.1 μ F
Q3
Q4
D2
L2
4.7 μ H
OUTPUT2
2.5V, 4A
C4
470 μ F
5 TON
28 CS1
CS2
16
1 OUT1
OUT2 15
R1
5m Ω
C7
0.22 μ F
10
2
REF
FB1
SKIP
FB2
6
14
5V
100k Ω
R2
10m Ω
23
GND
PGOOD
7
POWER-GOOD
INDICATOR
Figure 1. Standard Application Circuit
______________________________________________________________________________________
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1845ETX-TG068 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1845EVKIT | 功能描述:电源管理IC开发工具 Evaluation Kit for the MAX1845 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 |
| MAX1846EUB | 功能描述:电流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX1846EUB+ | 功能描述:电流型 PWM 控制器 Current-Mode Invert PWM Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX1846EUB+T | 功能描述:电流型 PWM 控制器 Current-Mode Invert PWM Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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