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参数资料
| 型号： | MAX1961 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining |
| 中文描述： | 2.35V至5.5V、0.5%精度、1MHz PWM降压型控制器，带有电压裕量控制 |
| 文件页数： | 14/29页 |
| 文件大小： | 455K |
| 代理商： | MAX1961 |
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M
ates a 128 clock cycle counter. If the current limit is pre-
sent at the end of this count, the controller remains off
until the input voltage is removed and re-applied, or the
device is re-enabled with CTL1 and CTL2. The 128-cycle
counter is reset when four successive DH pulses are
observed, without activating the current limit.
At maximum load, the low excursion of inductor current,
I
VALLEY(MAX)
, is:
The current-limit threshold (V
CLT
) is set by connecting a
resistor (R
ILIM
) from ILIM to GND. The range for this
resistor is 100k
to 400k
. Set current-limit threshold as
follows:
V
CLT
= R
ILIM
×
0.714μA
Connecting ILIM to V
DD
sets the threshold to a default
value of 75mV.
To prevent the current limit from falsely triggering, V
CLT
divided by the low-side MOSFET R
DS(ON)
must exceed
the maximum value of I
VALLEY
. The maximum value of
low-side MOSFET R
DS(ON)
should be used:
V
CLT
> R
DS(ON)MAX
x I
VALLEY(MAX)
A limitation of sensing current across MOSFET on-resis-
tance is that the MOSFET on-resistance varies signifi-
cantly from MOSFET to MOSFET and over temperature.
Consequently, this current-sensing method may not be
suitable if a precise current limit is required. If better
accuracy is needed, use the MAX1962 with a current-
sense resistor.
Current-Sense Resistor (MAX1962)
The MAX1962 uses a current-sense resistor connected
from the inductor to the output with Kelvin sense connec-
tions. The current-sense voltage is measured from CS to
OUT, and has a fixed threshold of 50mV. The MAX1962
current limit is triggered when the peak voltage across
the current-sense resistor, I
PEAK
×
R
SENSE
, exceeds
50mV. Once current sense is triggered, the controller
does not turn off, but continues to operate at the current
limit. This method of current sensing is more precise due
to the accuracy of the current-sense resistor. The cost of
this precision is that it requires an extra component and
is slightly less efficient due to the loss in the current-
sense resistance.
Inductor Resistance Current Sense (MAX1962)
Alternately, the inductor resistance can be used to
sense current in place of a current-sense resistor. To
do this, connect a series RC network in parallel with the
inductor (Figure 4). Choose a resistor value less than
40
to avoid offsets due to CS input current. Calculate
the capacitor value from the formula C = 2L / (R
L
×
R).
The effective current-sense resistance (R
SENSE
) equals
R
L
. Current-sense accuracy then depends on the accu-
racy of the inductor resistance. Note that the current-
sense signal is delayed due to the RC filter time
constant. Consequently, inductor current may over-
shoot (by as much as 2x) when a fast short occurs.
I
I
LIR
2
I
VALLEY MAX
LOAD MAX
LOAD MAX
(
)
(
)
(
)
×
=
-
2.35V to 5.5V, 0.5% Accurate, 1MHz PWM
Step-Down Controllers with Voltage Margining
14
______________________________________________________________________________________
I
PEAK
I
LOAD
I
VALLEY
I
TIME
Figure 3. Inductor Current Waveform
DH
L
R
L
R
R = 33
0.22
μ
H, 2.8mW,
I
LIMIT
= 18A
C
C = 4.7
μ
F
LX
DL
CS
OUT
MAX1962
Figure 4. Using the Inductor Resistance as a Current-Sense
Resistor with the MAX1962
相关PDF资料 |
PDF描述 |
|---|---|
| MAX1962 | 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining |
| MAX1962EEP | 2.35V to 5.5V, 0.5% Accurate, 1MHz PWM Step-Down Controllers with Voltage Margining |
| MAX19700 | 10-Bit, 45Msps, Ultra-Low-Power Analog Front-End |
| MAX19705 | 10-Bit, 45Msps, Ultra-Low-Power Analog Front-End |
| MAX19706 | 10-Bit, 45Msps, Ultra-Low-Power Analog Front-End |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1961EEP | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1961EEP+ | 功能描述:DC/DC 开关控制器 1MHz PWM Step-Down RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1961EEP+T | 功能描述:DC/DC 开关控制器 1MHz PWM Step-Down RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1961EEP-T | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX1962EEP | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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