参数资料
| 型号： | SP6121CN-L |
| 厂商： | Exar Corporation |
| 文件页数： | 9/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8NSOIC |
| 标准包装： | 98 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 560kHz |
| 占空比： | 100% |
| 电源电压： | 3 V ~ 5.5 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
APPLICATIONS INFORMATION
while the inductor current ramps up or down to
the value corresponding to the new load current.
Additionally, the ESR in the output capacitor
causes a step in the output voltage equal to the
ESR value multiplied by the change in load
current. Because of the fast transient response
provided by the SP6121 when exposed to output
load transient, the output capacitor is typically
chosen for ESR , not for capacitance value.
The output capacitor’s ESR, combined with the
inductor ripple current, is typically the main
contributor to output voltage ripple. The maxi-
mum allowable ESR required to maintain a
specified output voltage ripple can be calculated
by:
Panasonic offers the SP series of specialty poly-
mer aluminum electrolytic surface mount ca-
pacitors. These capacitors have a lower ESR
than tantalum capacitors, reducing the total num-
ber of capacitance required for a given transient
response.
Input Capacitor Selection
The input capacitor should be selected for ripple
current rating, capacitance and voltage rating.
The input capacitor must meet the ripple current
requirement imposed by the switching current.
In continuous conduction mode, the source cur-
rent of the high-side MOSFET is approximately
a square wave of duty cycle V OUT / V IN . Most of
this current is supplied by the input bypass
R ESR ≤
? V OUT
I PP
capacitors. The RMS value of input capacitor
current is determined at the maximum output
current and under the assumption that the peak
where;
? V OUT = peak to peak output voltage ripple
I PP = peak to peak inductor ripple current
The total output ripple is a combination of the
ESR and the output capacitance value and can
be calculated as follows:
to peak inductor ripple current is low, it is given
by:
I CIN(rms) = I OUT(max) √ D(1 - D)
The worse case occurs when the duty cycle D is
50% and gives an RMS current value equal to
IOUT/2. Select input capacitors with adequate
ripple current rating to ensure reliable opera-
(
? V OUT = I PP (1 – D)
C OUT F S
)
2
+ (I PP R ESR ) 2
tion.
The power dissipated in the input capacitor is:
P CIN = I CIN ( rms ) R ESR ( CIN )
2
where;
D = duty cycle equal to V OUT /V IN
C OUT = output capacitance value
Recommended capacitors that can be used ef-
fectively in SP6121 applications are: low-ESR
aluminum electrolytic capacitors, OS-CON ca-
pacitors that provide a very high performance/
This can become a significant part of power
losses in a converter and reduce the overall
energy transfer efficiency.
The input voltage ripple primarily depends on
the input capacitor ESR and capacitance. Ignor-
ing the inductor ripple current, the input voltage
ripple can be determined by:
size ratio for electrolytic capacitors and low-
ESR tantalum capacitors. AVX TPS series and
? V IN = I OUT(MAX) R ESR(CIN) +
I OUT(MAX) V OUT (V IN - V OUT )
F S C IN V IN2
Kemet T510 surface mount capacitors are popu-
lar tantalum capacitors that work well in SP6121
applications. POSCAP from Sanyo is a solid
electrolytic chip capacitor that has low ESR and
high capacitance. For the same ESR value,
POSCAP has lower profile compared with tan-
talum capacitor.
The capacitor type suitable for the output ca-
pacitors can also be used for the input capaci-
tors. However, exercise extra caution when tan-
talum capacitors are considered. Tantalum ca-
pacitors are known for catastrophic failure when
exposed to surge current, and input capacitors
are prone to such surge current when power
Date: 11/29/04
SP6121 Low Voltage, Synchronous Step Down PWM Controller
9
? Copyright 2004 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP6121CN-L/TR | 功能描述:电压模式 PWM 控制器 Low Voltage, 8 Pin Synchronous, Cntrllr 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 |
| SP6121EB | 功能描述:电压模式 PWM 控制器 Low Voltage, 8 Pin Sync Buck 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 |
| SP6122 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters |
| SP6122_04 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters |
| SP6122ACU | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
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