参数资料
| 型号： | SP6121CN-L |
| 厂商： | Exar Corporation |
| 文件页数： | 13/16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
both the 30 μ A sink current present at the I SET pin
SP6121
V IN
and the 160mV built-in current limit threshold
+
160mV
- +
I SET
RSET
PDRV
Q1
C IN
have been designed with a positive temperature
coefficient of about 0.33%/C to provide first order
-
30 μ A
I SENSE
NDRV
Q2
L1
C OUT
V OUT
correction for current limit versus temperature.
This compensation relies on the high amount of
thermal coupling that typically exists between the
high side switch Q1 and the SP6121 due to the
compact size of the power supply. With this first
order compensation, the current limit trip point
Figure 6. Current Limit Setting
The value of R SET can be properly chosen based on
the desired current limit point I MAX and the internal
30 μ A pull down current available on the I SET pin
according to the following expression:
does not need to be set to an increased level at room
temperature to guarantee a desired output current
level at higher temperatures.
Output Voltage Program
As shown in Figure 7(A), the voltage divider
R SET =
I MAX R DS(ON) - 160mV
I SET
connecting to the V FB pin programs the output
voltage according to
where,
I SET = 30 μ A (typ) sink current from the I SET pin.
R2
V OUT = 1.25 ( 1 + R1
)
Kelvin-Sense connections should be made di-
rectly at the drain and source of Q1.
The R DS(ON) sensing scheme implemented in the
where 1.25V is the internal reference voltage.
Select R2 in the range of 10k to 100k, and R1 can
be calculated using
SP6121 provides two additional features that
enhance the performance of the overcurrent
R1 =
R2(V OUT - 1.25)
1.25
2.5V - V OUT
function. First, an internal sample and hold filter
connected after the main current-sense com-
parator, prevents that noise spikes or very short
and mild overload conditions, that could occur
during a load transient, spuriously activate the
current limit circuitry. This typically eliminates
the need of using any external filtering that would
be otherwise required. Additionally, since the
R DS(ON) has a positive temperature coefficient,
For output voltage less than 1.25V, a simple
circuit shown in Figure 7(B) can be used in
which V REF is an external voltage reference
greater than 1.25V. For simplicity, use the same
resistor value for R1 and R2, then R3 is deter-
mined as follows,
(V REF - 1.25)R1
R3 =
V OUT > 1.25V
V REF
V OUT < 1.25V
?
SP6121
V FB
R1
?
SP6121
V FB
R3
R1
A
R2
B
R2
Figure 7(A) A voltage divider connected to the V FB pin programs the output voltage. (B) A simple circuit using one
external voltage reference programs the output voltages less than 1.25V.
Date: 11/29/04
SP6121 Low Voltage, Synchronous Step Down PWM Controller
13
? 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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