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参数资料
| 型号： | ISL6261AEVAL1Z |
| 厂商： | Intersil |
| 文件页数： | 19/34页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD 1 FOR ISL6261A |
| 标准包装： | 1 |
| 系列： | * |
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ISL6261A
The NTC thermistor ’s resistance is approximately given by
the following formula:
Once R NTCTo and R s is designed, the actual NTC resistance
at T 2 and the actual T 2 temperature can be found in:
b ? (
?
T + 273 To + 273
R ( T ) = R ? e
T 2 _ actual =
) + 1 ( 273 + T o )
1 R NTC _ T 2
1 1
) (EQ. 6)
NTC NTCTo
T is the temperature of the NTC thermistor and b is a
constant determined by the thermistor material. T o is the
reference temperature at which the approximation is
R NTC _ T 2 = 2 . 78 k Ω + R NTC _ T 1
1
ln(
b R NTCTo
? 273
(EQ. 13)
(EQ. 14)
derived. The most commonly used T o is +25 ° C. For most
commercial NTC thermistors, there is b = 2750k, 2600k,
4500k or 4250k.
From the operation principle of VR_TT#, the NTC resistor
satisfies the following equation group:
One example of using Equations 10, 11 and 12 to design a
thermal throttling circuit with the temperature hysteresis
+100 ° C to +105 ° C is illustrated as follows. Since T 1 = +105 ° C
and T 2 = +100 ° C, if we use a Panasonic NTC with b = 4700,
Equation 9 gives the required NTC nominal resistance as
R NTC (T 1 ) + R s =
R NTC (T 2 ) + R s =
1 . 20 V
60 μ A
1 . 23 V
54 μ A
= 20 k ?
= 22 . 78 k ?
(EQ. 7)
(EQ. 8)
R NTC_To = 431 k ?
The NTC thermistor datasheet gives the resistance ratio as
0.03956 at +100 ° C and 0.03322 at +105 ° C. The b value of
4700k in Panasonic datasheet only covers up to +85 ° C;
therefore, using Equation 11 is more accurate for +100 ° C
From Equation 7 and Equation 8, the following can be
derived:
R NTC (T 2 ) ? R NTC (T 1 ) = 2 . 78 k ?
(EQ. 9)
design and the required NTC nominal resistance at +25 ° C is
438k Ω . The closest NTC resistor value from manufacturers
is 470k Ω . So Equation 12 gives the series resistance as
follows:
b ? (
)
2 . 78 k ? ? e
R NTCTo =
b ? (
b ? (
)
)
? e
e
Substitution of Equation 6 into Equation 9 yields the required
nominal NTC resistor value:
1
T o + 273
(EQ. 10)
1 1
T 2 + 273 T 1 + 273
In some cases, the constant b is not accurate enough to
approximate the resistor value; manufacturers provide the
resistor ratio information at different temperatures. The
nominal NTC resistor value may be expressed in another
way as follows:
R s = 20 k Ω ? R NTC _ 105 C = 20 k Ω ? 15 . 61 k Ω = 4 . 39 k Ω
The closest standard value is 4.42k Ω . Furthermore,
Equation 13 gives the NTC resistance at T 2 :
R NTC _ T 2 = 2 . 78 k Ω + R NTC _ T 1 = 18 . 39 k Ω
The NTC branch is designed to have a 470k NTC and a
4.42k resistor in series. The part number of the NTC
thermistor is ERTJ0EV474J. It is a 0402 package. The NTC
thermistor should be placed in the spot that gives the best
indication of the temperature of the voltage regulator. The
actual temperature hysteretic window is approximately
R NTCTo =
2 . 78 k ?
Λ Λ
R NTC (T 2 ) ? R NTC (T 1 )
(EQ. 11)
+105°C to +100°C.
Λ
where R NTC ( T ) is the normalized NTC resistance to its
nominal value. The normalized resistor value on most NTC
thermistor datasheets is based on the value at +25°C.
Once the NTC thermistor resistor is determined, the series
resistor can be derived by:
R s =
1 . 20 V
60 μ A
? R NTC (T 1 ) = 20 k ? ? R NTC_T 1
19
(EQ. 12)
FN6354.3
November 5, 2009
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相关代理商/技术参数 |
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| ISL6261AEVAL2Z | 功能描述:EVAL BOARD 2 FOR ISL6261A RoHS:是 类别:编程器，开发系统 >> 评估板 - 线性稳压器 (LDO) 系列:* 产品变化通告:1Q2012 Discontinuation 30/Mar/2012 设计资源:NCP590MNDPTAGEVB Gerber Files 标准包装:1 系列:- 每 IC 通道数:2 - 双 输出电压:1.8V，2.8V 电流 - 输出:300mA 输入电压:2.1 ~ 5.5 V 稳压器类型:正，固定式 工作温度:-40°C ~ 85°C 板类型:完全填充 已供物品:板 已用 IC / 零件:NCP590MNDP 其它名称:NCP590MNDPTAGEVB-NDNCP590MNDPTAGEVBOS |
| ISL6261AIRZ | 功能描述:DC/DC 开关控制器 ONE-PHS INT DC/DC BUCK CNTRLR IMVP-6 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| ISL6261AIRZ-T | 功能描述:DC/DC 开关控制器 ONE-PHS INT DC/DC BUCK CNTRLR IMVP-6 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| ISL6261CR7Z | 功能描述:IC CTRLR BUCK 1PHASE 48-VFQFN EP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| ISL6261CR7Z-T | 功能描述:IC CTRLR BUCK 1PHASE 48-VFQFN-EP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
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