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参数资料
| 型号： | A8450KLB |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 11/17页 |
| 文件大小： | 546K |
| 描述： | IC REG QD BUCK/LINEAR 24-SOIC |
| 标准包装： | 31 |
| 拓扑： | 降压（降压）（1），线性（LDO）（4） |
| 功能： | 车载 |
| 输出数： | 4 |
| 电压/电流 - 输出 1： | 5.7V，1.2A |
| 电压/电流 - 输出 2： | 5V，200mA |
| 电压/电流 - 输出 3： | 5V，200mA |
| 带 LED 驱动器： | 无 |
| 带监控器： | 无 |
| 带序列发生器： | 是 |
| 电源电压： | 6 V ~ 45 V |
| 工作温度： | -40°C ~ 135°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 24-SOIC W |
| 包装： | 管件 |
Automotive Multioutput Voltage Regulator
A8450
11
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Component Selection
Output Inductor (L1). This inductor must be rated to handle the
total load current, I
LOAD
. In addition, the value chosen must keep
the ripple current to a reasonable level. A typical selection is a
power inductor rated at 100 糎 and 1.3 A.
The worse case ripple current, I
RIPPLE(max)
(mA), can be calcu-
lated as
I
RIPPLE(max)
= V
L1OFF
?SPAN class="pst A8450KLBTR-T_2464169_10">
t
OFF
D L
L1
where L
L1
(糎) is the inductance for the selected component, and
V
L1OFF
is the voltage (V) through the inductor when the A8450 is
in the quiescent state
V
L1OFF
= V
REG(max)
+ V
D1
+ (I
LOAD ?/SPAN>
R
L1
)
where V
D1
(V) is the voltage drop on diode D1, I
LOAD
(mA) is
the total load current, and R
L1
is the specified DC resistence (?
for the selected inductor at its rated temperature.
The frequency, f
PWM
(Hz), of the switching regulator in the buck
converter can then be estimated by
f
PWM
= 1/(t
ON
+ t
OFF
)
where t
ON
(約) is calculated as
t
ON
= I
RIPPLE(max)
?SPAN class="pst A8450KLBTR-T_2464169_2">
L
L1
D V
L1ON
and V
L1ON
(V) as
V
L1ON
= V
BB
(I
LOAD
?SPAN class="pst A8450KLBTR-T_2464169_2">
R
DSON(max)
)
(I
LOAD ?/SPAN>
R
L1
) V
REG(max)
Example
Given a typical application with V
BB
= 14 V, t
OFF
= 4.75 約, and
I
LOAD
= 550 mA. (Note that the value for t
OFF
is constant for V
BB
> 12 V, as shown in figure 3.)
Given also a 100 糎 power inductor rated at 400 m?for 125篊.
(Note that temperature ratings for inductors may include self-
heating effects. If a 125篊 rating includes a self-heating tempera-
ture rise of 20篊 at maximum current, then the actual ambient
temperature, T
A
, cannot exceed 105篊.)
V
L1OFF
= 5.8 + 0.8 + (0.550
?
0.400) = 6.821 V
I
RIPPLE(max)
= 6.821
?/DIV>
4.75 D 100 = 0.324 A
V
L1ON
= 14 (0.550
?/DIV>
0.750) (0.550
?/DIV>
0.400)
5.8 = 7.56 V
t
ON
= 0.324
?/DIV>
100 D 7.56 = 4.3 約
f
PWM
= 1/(4.3 + 4.75) = 111 kHz
In the case of a shorted output, the buck converter could reach
its internal current limit, I
DSLIM
, of 1.2 A typical. To ensure safe
operation, the I
SAT
rating for the selected inductor should be
greater than 1.4 A. However, if the external current limit resistors,
R3 and R4, selected for the 3.3 V and adjustable (1.2 V to 3.3 V)
regulators, are rated such that the total inductor current, I
LOAD
,
could never reach that internal current limit, then an inductor can
be selected that has an I
SAT
rating closer to the calculated output
current of the device, I
LOAD
, plus the maximum ripple current,
I
RIPPLE(max)
.
Higher inductor values can be chosen to lower I
RIPPLE
. This may
be an option if it is desired to increase the total maximum current
that is drawn from the switching regulator. The maximum total
current available, I
LOAD
(mA), is calculated as
I
LOAD
= I
DSLIM
(I
RIPPLE(max)
D 2)
Catch Diode (D1). The Schottky catch diode should be rated to
handle 1.2 times the maximum load current, I
LOAD
, because the
duty cycle at low input voltages, V
BB
, can be very close to 100%.
The voltage rating should be higher than the maximum input
voltage, V
BB(max)
, expected during any operating condition.
VREG Output Capacitor (COUT). Voltage ripple in the
VREG output is the main consideration when selecting the
VREG output capacitor, COUT. The peak-to-peak output voltage
ripple, V
RIPPLE(p-p)
(mV), is calculated as
V
RIPPLE(p-p)
= I
RIPPLE
?SPAN class="pst A8450KLBTR-T_2464169_10">
ESR
COUT
with ESR in ohms. It is recommended that the maximum level of
V
RIPPLE(p-p)
be less than 200 mV.
For electrolytic output capacitors, a low-ESR type is recom-
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相关代理商/技术参数 |
参数描述 |
|---|---|
| A8450KLB-T | 功能描述:IC REG QD BUCK/LINEAR 24-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1） 功能:任何功能 输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR |
| A8450KLB-T | 制造商:Allegro MicroSystems 功能描述:Voltage Regulator IC |
| A8450KLBTR | 功能描述:IC REG QD BUCK/LINEAR 24-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1） 功能:任何功能 输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR |
| A8450KLBTR-T | 功能描述:IC REG QD BUCK/LINEAR 24-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| A845DSC | 制造商:Pentair Technical Products / Hoffman 功能描述:DSC Box 8.00x4.00x4.75 Gray, 8.00x4.00x3.75, Steel |
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