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| 型号： | SP6121CN-L/TR |
| 厂商： | Exar Corporation |
| 文件页数： | 6/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8NSOIC |
| 标准包装： | 2,500 |
| 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： | 带卷 (TR) |
THEORY OF OPERATION
clamp and then gradually charges preventing
the error amplifier from forcing the loop to
maximum duty cycle. As the COMP voltage
crosses about 1V (valley voltage of the PWM
ramp), the driver begins to switch the high side
MOSFET with narrow pulses in an effort to
keep the converter output regulated . The SP6121
operates at low duty cycle as the COMP voltage
increases above 1V. As the error amp reference
ramps upward, the driver pulses widen until a
steady state value is reached and the output
voltage is regulated to the final value ending the
soft start charge cycle.
COMP
1V
0.7 V
0.3 V
0V
Hiccup Mode
When the converter enters a fault mode, the
SP6121 holds the high side and low side
MOSFETs off for a finite period of time. Pro-
vided that the SP6121 is enabled, this time is set
by the internal charge of the SS capacitor. In the
event of an over-current condition, the current
sense comparator sets the fault latch, which in
turn discharge the internal SS capacitor, the
COMP pin and holds the output drivers off.
During this condition, the SP6121 stays off for
the time it takes to discharge the COMP pin
down below the 0.3V shutdown threshold. As
soon as the COMP pin reaches 0.3V, the fault
latch is reset and the SP6121 is allowed to
attempt restart just like during a normal soft start
cycle. The COMP pin has to charge back to 1V
before any output switching can take place. At
this point, the regulator attempts to restart nor-
mally by delivering short gate pulses to the
output switches. If the over-current condition
Internal SS
Voltage
Error Amp
Reference
Voltage
1.25V
0V
I(L)
Inductor
Current
0A
V(V CC )
dVss/dt = 0.4V/ms
V OUT = V (REF) * (1+R1/R2)
persists, the regulator will be kept off for the
total time that it takes to charge the internal soft-
start capacitor to within 1V from the input
supply voltage V CC plus the time required by the
COMP voltage to cross the 1V threshold. This
total time is typically several milli-seconds and
minimizes thermal stress to the regulator com-
ponents as the over-current condition persists.
The waveforms that describe the hiccup mode
operation are shown in Figure 2.
V (ISET) -V (ISENSE)
160 mV
0V
COMP
Voltage
3V
FAULT
0V
V(V CC )
SWN
Voltage
1.0 V
0.3 V
0V
V (VCC)
PDRV
Voltage
0V
0V
TIME
Figure 1. SP6121 Soft Start Waveforms
TIME
Figure 2. SP6121 Hiccup mode waveforms
Date: 11/29/04
SP6121 Low Voltage, Synchronous Step Down PWM Controller
6
? Copyright 2004 Sipex Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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: |
| SP6122ACU/TR | 制造商:Exar Corporation 功能描述: |
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