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| 型号： | MAX8513EEI+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 28/35页 |
| 文件大小： | 0K |
| 描述： | IC REG TRPL BUCK/LINEAR 28QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 拓扑： | 降压（降压）（1），线性（LDO）（2） |
| 功能： | 任何功能 |
| 输出数： | 3 |
| 频率 - 开关： | 250kHz ~ 1.5MHz |
| 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： | 无 |
| 电源电压： | 4.5 V ~ 28 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 28-QSOP |
| 包装： | 带卷 (TR) |
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Wide-Input, High-Frequency, Triple-Output Supplies
with Voltage Monitor and Power-On Reset
? 1 . 3 × 2 π × C R ,
BW MAX = MIN ?
?
?
?
β ( MIN ) =
A third pole occurs due to the input capacitance of the
NMOS transistor ’s gate, C q (C iss from the MOSFET
data sheet), and the compensation resistor (R A ). If an
NPN bipolar transistor is used instead, this third pole
can be calculated from the base capacitance (C q =
C IBO from the NPN data sheet). To ensure stability, a
zero is added to the loop from the resistor (R A ) and
capacitor (C A ).
For good stability and transient response, first pick
C OUT2 at approximately 6.8μF/A of load current. For the
Typical Applications Circuit , C OUT2 is a 10μF ceramic
capacitor. Ensure that the zero formed from the ESR of
C OUT2 is greater than the maximum bandwidth BW MAX
(calculated below). The maximum bandwidth should
also be less than the pole created by Q3’s gate capaci-
tance (Cq) and the compensation resistor (R A ).
? 1 1 ?
?
G C
? 1 1 ?
×
? ?
? 10 2 π × R ESR _ COUT 2 C OUT ?
The following equations set the compensation zero a
decade and a half below the maximum load pole and
ensure the above constraint is met. Choose the larger
of the two values for C A .
drive current. The selected MOSFET must have the gate
threshold voltage meet the following criteria:
V GS _ MAX ≤ V DRV 2 - V OUT 2
where V DRV2 is equal to 7.75V or V SUP2 - 1.5V
(whichever is less), and V GSMAX is the maximum gate
voltage required to yield the on-resistance specified by
the manufacturer’s data sheet. Logic-gate MOSFETs
are recommended.
NPN-Transistor Selection
The MAX8513/MAX8514s’ OUT2 can use a less expen-
sive NPN transistor as the series pass transistor. In
selecting the appropriate NPN transistor, make sure the
beta is large enough so the regulator can provide
enough base current. The minimum beta of the transis-
tor is:
I OUT 2(MAX )
4 mA
In addition, to avoid premature dropout, V CE_SAT ≤
V IN_MIN - V OUT2 .
OUT3_ Transistor Selection
The pass transistors must meet specifications for cur-
rent gain ( β ), input capacitance, collector-emitter satu-
ration voltage, and power dissipation. The transistor’s
8 × V OUT OUT q C 2 × g C ( MAX ) ×
× C
× C × G
( )
g C ( MAX ) × R ESR _ COUT 2 + 1
13 ×
g C ( MAX ) V OUT 2 + I OUT 2 ( MAX )
? 16 10 ×
(
)
g C ( MAX ) V OUT 2 + I OUT 2 ( MAX )
? ? ESR _ COUT 2 OUT ? C q
I OUT 3 P = ? I DRV 3 P _ MIN - - BE ? β
R A = 10 10 × ×
?
?
?
?
?
?
C A = MAX ?
?
? G C 2 × g C ( MAX )
?
? R C
V OUT 2 C OUT 2
C A
( g C ( MAX ) × R ESR _ COUT 2 + 1 )
( g C ( MAX ) V OUT 2 + I OUT 2 ( MAX ) )
×
,
current gain limits the guaranteed maximum output cur-
rent to:
? V ?
? R12 ?
where I DRV3P_MIN is the minimum base-drive current
and R12 is the pullup resistor connected between the
transistor ’s base and emitter (see the Typical
Applications Circuits ). In addition, to avoid premature
dropout V CE_SAT ≤ V IN_MIN - V OUT3 . Furthermore, the
transistor’s current gain increases the linear regulator’s
DC loop gain (see the Stability Requirements section),
so excessive gain destabilizes the output. Therefore,
transistors with current gain over 100 at the maximum
output current, such as Darlington transistors, are not
recommended. The transistor’s input capacitance and
input resistance also create a second pole, which could
be low enough to destabilize the LDO when the output
MOSFET Transistor Selection
MAX8513/MAX8514s’ OUT2 uses N-channel MOSFETs
as the series pass transistor to improve efficiency for
high output current by not requiring a large amount of
is heavily loaded.
The transistor’s saturation voltage at the maximum output
current determines the minimum input-to-output voltage
differential that the linear regulator supports. Alternately,
28
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8513EVKIT | 功能描述:电源管理IC开发工具 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 |
| MAX8514AEI | 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 |
| MAX8514AEI-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 |
| MAX8514EEI | 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 |
| MAX8514EEI-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 |
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