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參數資料
| 型號： | SP6121CN |
| 英文描述： | Low Voltage, Synchronous Step Down PWM Controller Ideal for 2A to 10A, Small Footprint, DC-DC Power Converters |
| 中文描述： | 低電壓，為第2A同步降壓PWM控制器的理想下至10A，占地面積小，DC - DC電源轉換器 |
| 文件頁數： | 13/16頁 |
| 文件大?。?/td> | 358K |
| 代理商： | SP6121CN |
Date: 5/25/04
SP6121 Low Voltage, Synchronous Step Down PWM Controller Copyright 2004 Sipex Corporation
13
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.
A
B
V
REF
V
FB
V
FB
V
OUT
< 1.25V
V
OUT
> 1.25V
SP6121
SP6121
R1
R2
R1
R2
R3
C
IN
I
SET
V
IN
PDRV
SP6121
NDRV
I
SENSE
V
OUT
L1
C
OUT
RSET
Q1
Q2
+
-
+
-
30
μ
A
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:
R
SET
= I
MAX
R
DS(ON)
- 160mV
I
SET
where,
I
SET
= 30
μ
A (typ) sink current from the I
SET
pin.
Kelvin-Sense connections should be made di-
rectly at the drain and source of Q1.
The R
DS(ON)
sensing scheme implemented in the
SP6121 provides two additional features that
enhance the performance of the overcurrent
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,
both the 30
μ
A sink current present at the I
SET
pin
and the 160mV built-in current limit threshold
have been designed with a positive temperature
coefficient of about 0.33%/C to provide first order
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
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
connecting to the V
FB
pin programs the output
voltage according to
V
OUT
= 1.25
(
1 + R1
)
R2
where 1.25V is the internal reference voltage.
Select R2 in the range of 10k to 100k, and R1 can
be calculated using
R2(V
OUT
- 1.25)
R1 =
1.25
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
2.5V - V
OUT
R3 =
APPLICATIONS INFORMATION: Continued
相關PDF資料 |
PDF描述 |
|---|---|
| SP6121EB | Demo Board Manual |
| SP6132H | High Voltage, 300KHz Synchronous PWM Controller |
| SP6132HEU | High Voltage, 300KHz Synchronous PWM Controller |
| SP6134 | Dual Supply Synchronous Buck Controller |
| SP6134CU | Dual Supply Synchronous Buck Controller |
相關代理商/技術參數 |
參數描述 |
|---|---|
| SP6121CN/TR | 功能描述:開關變換器、穩(wěn)壓器與控制器 Low Voltage, 8 Pin Synchronous, Cntrllr RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| SP6121CN-L | 功能描述:電壓模式 PWM 控制器 Low Voltage, 8 Pin Synchronous, Cntrllr RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| SP6121CN-L/TR | 功能描述:電壓模式 PWM 控制器 Low Voltage, 8 Pin Synchronous, Cntrllr RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| SP6121EB | 功能描述:電壓模式 PWM 控制器 Low Voltage, 8 Pin Sync Buck Controller RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| SP6122 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Voltage, Micro 8, PFET, Buck Controller Ideal for 1A to 5A, Small Footprint, DC-DC Power Converters |
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