- 您现在的位置：买卖IC网 > PDF目录1839 > MAX17020ETJ+ (Maxim Integrated Products)IC CTLR PWM DUAL STEP DN 32-TQFN PDF资料下载
参数资料
| 型号： | MAX17020ETJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 26/34页 |
| 文件大小： | 0K |
| 描述： | IC CTLR PWM DUAL STEP DN 32-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 系列： | Quick-PWM™ |
| 应用： | 电源 |
| 电流 - 电源： | 1mA |
| 电源电压： | 6 V ~ 24 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 管件 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页当前第26页第27页第28页第29页第30页第31页第32页第33页第34页
Dual Quick-PWM Step-Down Controller
with Low-Power LDO, RTC Regulator
V RIPPLE × ( V IN ? V OUT )
V IN SW LOAD ( MAX ) × LIR
× f
× I
≈ ( Δ I LOAD ( MAX ) ) 2 × L
2 × C OUT × V OUT
lower than this grant no further size-reduction bene-
fit. The optimum operating point is usually found
between 20% and 50% ripple current. When pulse
skipping ( SKIP low and light loads), the inductor
value also determines the load-current value at
which PFM/PWM switchover occurs.
Inductor Selection
The switching frequency and inductor operating point
determine the inductor value as follows:
L =
For example: I LOAD(MAX) = 4A, V IN = 12V, V OUT2 =
2.5V, f SW = 355kHz, 30% ripple current or LIR = 0.3:
where t OFF(MIN) is the minimum off-time (see the
Electrical Characteristics table) and K is from Table 3.
The amount of overshoot during a full-load to no-load tran-
sient due to stored inductor energy can be calculated as:
V SOAR
Setting the Current Limit
The minimum current-limit threshold must be great
enough to support the maximum load current when the
current limit is at the minimum tolerance value. The val-
ley of the inductor current occurs at I LOAD(MAX) minus
half the ripple current; therefore:
I LIM ( VAL ) > I LOAD ( MAX ) ? ?
?
?
?
L =
2 . 5 V × ( 12 V ? 2 . 5 V )
12 V × 355 kHz × 4 A × 0 . 3
= 4 . 65 μH
? I LOAD(MAX ) × LIR ?
2
Find a low-loss inductor having the lowest possible DC
resistance that fits in the allotted dimensions. Ferrite
cores are often the best choice, although powdered
iron is inexpensive and can work well at 200kHz. The
core must be large enough not to saturate at the peak
inductor current (I PEAK ):
where I LIM(VAL) equals the minimum valley current-limit
threshold voltage divided by the current-sense resis-
tance (R SENSE ). When using a 100k Ω ILIM resistor, the
minimum valley current-limit threshold is 40mV.
Connect a resistor between ILIM_ and analog ground
(AGND) to set the adjustable current-limit threshold. The
I PEAK LOAD ( MAX ) × ? 1 +
= I
2 ?
?
?
LIR ?
?
valley current-limit threshold is approximately 1/10 the
ILIM voltage formed by the external resistance and inter-
nal 5μA current source. The 40k Ω to 400k Ω adjustment
Most inductor manufacturers provide inductors in stan-
dard values, such as 1.0μH, 1.5μH, 2.2μH, 3.3μH, etc.
Also look for nonstandard values, which can provide a
better compromise in LIR across the input voltage
range. If using a swinging inductor (where the no-load
inductance decreases linearly with increasing current),
evaluate the LIR with properly scaled inductance values.
Transient Response
The inductor ripple current also impacts transient-
response performance, especially at low V IN - V OUT dif-
ferentials. Low inductor values allow the inductor
current to slew faster, replenishing charge removed
from the output filter capacitors by a sudden load step.
The amount of output sag is also a function of the maxi-
mum duty factor, which can be calculated from the on-
time and minimum off-time:
range corresponds to a 20mV to 200mV valley current-
limit threshold. When adjusting the current limit, use 1%
tolerance resistors to prevent significant inaccuracy in
the valley current-limit tolerance.
Output Capacitor Selection
The output filter capacitor must have low enough equiv-
alent series resistance (ESR) to meet output ripple and
load-transient requirements, yet have high enough ESR
to satisfy stability requirements.
For processor core voltage converters and other appli-
cations where the output is subject to violent load tran-
sients, the output capacitor ’s size depends on how
much ESR is needed to prevent the output from dipping
too low under a load transient. Ignoring the sag due to
finite capacitance:
(
)
× ? ? OUT ? + t OFF ( M I N ) ?
L × Δ I LOAD ( MAX )
? ? ( V IN ? V OUT ) × K ? ?
2 × C OUT × V OUT ? ? ? ? t OFF ( MIN ) ?
? ? ?
? ?
R ESR ≤
V SAG =
2 ? ? V K ? ?
? ? V IN ? ?
V IN
V STEP
Δ I LOAD ( MAX )
In applications without large and fast load transients,
the output capacitor’s size often depends on how much
ESR is needed to maintain an acceptable level of out-
put voltage ripple. The output ripple voltage of a step-
down controller equals the total inductor ripple current
26
______________________________________________________________________________________
相关PDF资料 |
PDF描述 |
|---|---|
| MAX17022ETA+T | IC GAUGE 1WIRE UART 8TDFN |
| MAX17024ETD+T | IC REG CTRLR DIVIDER PWM 14TDFN |
| MAX17028GTJ+ | IC PWM CTRL IMVP-6.5/GMCH 32TQFN |
| MAX17030GTL+ | IC CTRLR VID QUICK-PWM 40-TQFN |
| MAX1703ESE | IC REG BOOST SYNC 5V/ADJ 16SOIC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX17020ETJ+ | 功能描述:电压模式 PWM 控制器 Quick-PWM Step-Down Controller 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 |
| MAX17020ETJ+T | 功能描述:电压模式 PWM 控制器 Quick-PWM Step-Down Controller 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 |
| MAX17020EVKIT+ | 制造商:Maxim Integrated Products 功能描述:SINGLE QUICK-PWM STEP-DOWN CONTROLL - Boxed Product (Development Kits) |
| MAX17021EVKIT+ | 功能描述:电源管理IC开发工具 MAX17021 Eval Kit 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 |
| MAX17021GTL+ | 功能描述:电压模式 PWM 控制器 Dual-Phase, Quick-Pw M Controllers For Im 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 |
发布紧急采购，3分钟左右您将得到回复。