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参数资料
| 型号： | MAX1964TEEE+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 23/30页 |
| 文件大小： | 0K |
| 描述： | IC POWER CTRLR/SEQUENCER 16QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 100 |
| 应用： | 电源控制器，序列发生器 |
| 输入电压： | 4.5 V ~ 28 V |
| 电流 - 电源： | 1.25mA |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-QSOP |
| 包装： | 管件 |
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Tracking/Sequencing Triple/Quintuple
Power-Supply Controllers
current and load resistance, the total DC loop gain
? 1 + ? BIAS FE ? ? V REF
V T ? ? ? ?
A V ( LDO ) ≈ ?
I LOAD ? ? ?
? POLE ( FB ) ≈
(A V(LDO) ) is approximately:
? 5 . 5 ? ? ? I h ? ?
? ?
where V T is 26mV, and I BIAS is the current through the
base-to-emitter resistor (R BE ). This bias resistor is typi-
cally 220 ? , providing approximately 3.2mA of bias cur-
rent.
The output capacitor creates the dominant pole.
However, the pass transistor ’ s input capacitance creates
a second pole in the system. Additionally, the output
capacitor ’ s ESR generate a zero, which may be used to
cancel the second pole if necessary. Therefore, in order
to achieve stable operation, use the following equations
to verify that the linear regulator is properly compensat-
ed:
1) First, determine the dominant pole set by the linear
regulator ’ s output capacitor and the load resistor:
1
π C OUT R ESR
Do not use output capacitors with more than 200m ? of
ESR. Typically, more output capacitance provides the
best solution, since this also reduces the output voltage
drop immediately after a load transient.
Linear Regulator Output Capacitors
Connect at least 1μF capacitor between the linear regu-
lator ’ s output and ground, as close to the MAX1964/
MAX1965 and external pass transistors as possible.
Depending on the selected pass transistor, larger
capacitor values may be required for stability (see
Stability Requirements ). Furthermore, the output capac-
itor ’ s equivalent series resistance (ESR) affects stability,
providing a zero that may be necessary to cancel the
second pole. Use output capacitors with an ESR less
than 200m ? to ensure stability and optimum transient
response.
Once the minimum capacitor value for stability is deter-
? POLE ( CLDO ) =
1
2 π C LDO R LOAD
=
I LOAD ( MAX )
2 π C LDO V LDO
mined, verify that the linear regulator ’ s output does not
contain excessive noise. Although adequate for stabili-
ty, small capacitor values may provide too much band-
? POLE ( CBE ) =
( )
=
unity-gain crossover = A V(LDO) ? POLE(CLDO)
2) Next, determine the second pole set by the base-to-
emitter capacitance (including the transistor ’ s input
capacitance), the transistor ’ s input resistance, and
the base-to-emitter pullup resistor:
1
2 π C BE R BE R IN ( BJT )
R BE I LOAD + V T h FE
2 π C BE R BE V T h FE
3) A third pole is set by the linear regulator ’ s feedback
resistance and the capacitance between FB_ and
GND (including 20pF stray capacitance).
width, making the linear regulator sensitive to noise.
Larger capacitor values reduce the bandwidth, thereby
reducing the regulator ’ s noise sensitivity.
For the negative linear regulator, if noise on the ground
reference causes the design to be marginally stable,
bypass the negative output back to its reference volt-
age (V REF , Figure 7). This technique reduces the differ-
ential noise on the output.
Base-Drive Noise Reduction
The high-impedance base driver is susceptible to sys-
tem noise, especially when the linear regulator is lightly
loaded. Capacitively coupled switching noise or induc-
tively coupled EMI onto the base drive causes fluctua-
tions in the base current, which appear as noise on the
linear regulator ’ s output. Keep the base-drive traces
? POLE ( FB ) =
1
2 π C FB ( R 1 R 2 )
away from the step-down converter and as short as
possible to minimize noise coupling. Resistors in series
with the gate drivers (DH and DL) reduce the LX
switching noise generated by the step-down converter
4) If the second and third pole occur well after unity-
gain crossover, the linear regulator will remain stable:
? POLE(FB) and ? POLE(CBE) >
2 ? POLE(CLDO) A V(LDO)
However, if the ESR zero occurs before unity-gain
crossover, cancel the zero with f POLE(FB) by changing
circuit components such that:
(Figure 5). Additionally, a bypass capacitor may be
placed across the base-to-emitter resistor (Figure 7).
This bypass capacitor, in addition to the transistor ’ s
input capacitance, could bring in a second pole that
will destabilize the linear regulator (see Stability
Requirements ). Therefore, the stability requirements
determine the maximum base-to-emitter capacitance:
______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1964TEEE+ | 功能描述:电流和电力监控器、调节器 Track/Seq Trpl/Wuint Power-Supply Ctlr RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1964TEEE+T | 功能描述:电流和电力监控器、调节器 Track/Seq Trpl/Wuint Power-Supply Ctlr RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1964TEEE-T | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1965TEEP | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1965TEEP-T | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
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