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| 型号： | ISL8126IRZ-TK |
| 厂商： | Intersil |
| 文件页数： | 29/39页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 32-QFN |
| 标准包装： | 1,000 |
| PWM 型： | 电压模式 |
| 输出数： | 2 |
| 频率 - 最大： | 1.5MHz |
| 占空比： | 90% |
| 电源电压： | 3 V ~ 5.6 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： | -40°C ~ 85°C |
| 封装/外壳： | 32-VFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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ISL8126
C max = ------------------------------
? IL + ------------- ? ? ? --------------- – t MIN_OFF ? ? ? ? RSENSE
2F SW
?
?
L
ICS = --------------------------------------------------------------------------------------------------------------------
temperature raise in the resistor package, recommend using 0.4.
Once R min has been calculated, solve for the maximum value of
L (EQ. 6)
R min ? DCR
and choose the next-lowest readily available value. Then
substitute the chosen value into the same equation and
re-calculate the value of R. Choose the 1% resistor standard
Equation 8 shows the sampling current, I CS , when using sensing
resistor
? V OUT 1 – D ?
(EQ. 8)
R ISEN
Similar to DCR current sensing approach, the resistive sensing
approach can be used with output voltage less than VCC - 1.8V.
CS ( n )
value closest to this re-calculated value of R. For example, when
V IN_MAX = 14.4V, V OUT = 2.5V, L = 1μH and DCR = 1.5m Ω , with
0402 package Equation 5 yields R MIN of 1476 Ω and Equation 6
yields C MAX of 0.45μF. By choosing 0.39μF and recalculating the
resistor it yields 1.69k Ω.
MOSFET r DS(ON) SENSING
I
ISEN
V IN
With the internal low-offset current amplifier, the capacitor
voltage V C is replicated across the sense resistor R ISEN .
Therefore, the current out of ISEN(n)B pin, I SEN , is proportional to
the inductor current. After 175ns blanking period with respect to
the falling edge of the PWM pulse of each channel, the I SEN
current is filtered and sampled for 175ns. The sampling current
I CS then can be derived as shown by Equation 7:
SAMPLE
AND
HOLD
-
+
ISEN(n)B
R ISEN
(PTC)
ISEN(n)A
I L
-
I L x r DS ( ON )
+
? I L + ------------- ? ? ? --------------- – t MIN_OFF ? ? ? ? DCR
2F SW
? ?
R ISEN
? V OUT 1 – D ?
L
ICS = --------------------------------------------------------------------------------------------------------
(EQ. 7)
ISL8126 INTERNAL CIRCUIT
N-CHANNEL
MOSFETs
EXTERNAL CIRCUIT
Where I L is the inductor DC current, F SW is the switching
frequency, and t MIN_OFF is 350ns.
RESISTIVE SENSING
For accurate current sense, a dedicated current-sense resistor
RSENSE in series with the output inductor can serve as the
current sense element (see Figure 20). This technique is more
accurate, but reduces overall converter efficiency due to the
additional power loss on the current sense element RSENSE.
FIGURE 21. MOSFET r DS(ON) CURRENT-SENSING CIRCUIT
The controller can also sense the channel load current by
sampling the voltage across the synchronous MOSFET r DS(ON)
(see Figure 21). The amplifier is ground-reference by connecting
the ISEN(n)A pin to the source of the synchronous MOSFET.
ISEN(n)B pin is connected to the synchronous MOSFET’S drain
through the current sense resistor R ISEN . The voltage across
R ISEN is equivalent to the voltage drop across the r DS(ON) of the
lower MOSFET while it is conducting. The resulting current out of
? I L + ------------- ? ? ? --------------- – t MIN_OFF ? ? ? ? r DS ( ON )
2F SW
? ?
I CS = -----------------------------------------------------------------------------------------------------------------
CS ( n )
UGATE(n)
PHASE(n)
LGATE(n)
ISL8216A
INTERNAL CIRCUIT
I
SAMPLE
AND
HOLD
+
-
V IN
ISEN(n)A
ISEN(n)B
IL
L
RSENSE
V OUT
C OUT
R ISEN(n)
the ISEN(n)B pin is proportional to the channel current I L .
Equation 9 shows the sampling current, I CS , when using MOSFET
r DS(ON) sensing.
? V OUT 1 – D ?
L (EQ. 9)
R ISEN
Both inductor DCR and MOSFET r DS(ON) value will increase as the
temperature increases. Therefore the sensed current will
increase as the temperature of the current sense element
increases. In order to compensate the temperature effect on the
sensed current signal, a Positive Temperature Coefficient (PTC)
resistor can be selected for the sense resistor R ISEN .
Overcurrent Protection
ISEN
FIGURE 20. SENSE RESISTOR IN SERIES WITH INDUCTOR
29
For overload and hard short condition, the overcurrent protection
reduces the regulator RMS output current much less than full
load by putting the controller into hiccup mode. A delay time,
equal to 3 soft-start intervals, is inserted to allow the disturbance
to be cleared out. After the delay time, the controller then
initiates a soft-start interval. If the output voltage comes up and
returns to the regulation, PGOOD transitions high. If the OC trip is
FN7892.1
August 16, 2012
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL8128IAZ-TK | 制造商:Intersil Corporation 功能描述:PB-FREE SYNC BUCK PWM CONT. W/ 4.5V-28V |
| ISL8130 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Advanced Single Universal Pulse-Width Modulation (PWM) Controller |
| ISL8130EVAL3Z | 制造商:Intersil Corporation 功能描述:ISL8130 EVALUATION BOARD 3 - 20LD QSOP - ROHS COMPLIANT - Bulk 制造商:Intersil Corporation 功能描述:BOARD EVAL FOR ISL8130 制造商:Intersil Corporation 功能描述:ISL8130 EVALUATION BOARD 3 - 20LD QSOP - RoHS COMPLIANT |
| ISL8130IAZ | 功能描述:IC REG CTRLR BST FLYBK VM 20QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL8130IAZ-T7A | 功能描述:电流型 PWM 控制器 PB-FREE SYNC BUCK PWM CONT. W/ 4.5V-28V INPUT,20LD QSOP, 250 RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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