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| 型号： | ISL6741IBZ-T |
| 厂商： | Intersil |
| 文件页数： | 22/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM CM 16-SOIC |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 2MHz |
| 占空比： | 100% |
| 电源电压： | 9 V ~ 16 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： | 无 |
| 工作温度： | -40°C ~ 105°C |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
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ISL6740, ISL6741
Other duty ranges are possible, but are still limited to a 2:1 ratio.
A block diagram of the feedback control loop follows in
The voltage applied to V ERROR must be scaled to the peak-to-
peak voltage on C T , and offset by the valley voltage. Since the
peak-to-peak C T voltage is 2.00V nominal, the voltage at the
output of U100A must be divided by 2.0V to obtain the desired
duty cycle. For example, if an 80% duty cycle was required at the
Figure 19.
PWM
POWER
STAGE
V OUT
minimum operating voltage, the output of U100A must be 1.60V
(80% of 2.00V). From (Equation 25), the divider voltage must be
set to 1.4V for the input voltage that corresponds to the 80% duty
ERROR AMPLIFIER
cycle.
ISOLATION
Z 2
It should be noted that the synchronous rectifiers (SRs), being
driven from the transformer secondary, are only gated on during
the ON time of the primary FETs. Conduction continues through
the body diodes during the OFF time when operating in
-
+
REF
Z 1
continuous inductor current mode. This mode of operation
usually results in significant conduction and switching losses in
the SR FETs. These losses may be reduced considerably by either
adding schottky diodes in parallel to the SR FETs or by driving the
SR FETs directly with a control signal.
Adding Regulation - Closed Loop Feedback
The second Typical Application schematic adds closed loop
feedback with isolation. The ISL6740EVAL2Z demonstration
platform implements this design and is available for evaluation.
The input voltage range was increased to 36V to 75V, which
FIGURE 19. CONTROL LOOP BLOCK DIAGRAM
The loop compensation is placed around the Error Amplifier (EA)
on the secondary side of the converter. A Type 3 error amplifier
configuration was selected.
V OUT
necessitates a few modifications to the open loop design. The
output inductor value was increased to 4.0 μ H, schottky rectifier
V ERR
-
+
REF
CR4 was added to minimize SR FET body diode conduction, the
turns ratio of the main transformer was changed to 4:3, and the
synchronous rectifier gate drives were modified. The design
process is essentially the same as it was for the unregulated
version, so only the feedback control loop design will be
discussed.
FIGURE 20. TYPE 3 ERROR AMPLIFIER
The control to output transfer function may be represented as [1]
1 + ------
v o V IN N S ω z
V S ? 2
1 + ---------------- + ? ------- ?
( Q )ω ? ω ?
R o
ω o ? L
The major components of the feedback control loop are a
programmable shunt regulator and an opto-coupler. The opto-
coupler is used to transfer the error signal across the isolation
barrier. The opto-coupler offers a convenient means to cross the
isolation barrier, but it adds complexity to the feedback control
loop. It adds a pole at about 10kHz and a significant amount of
gain variation due the current transfer ratio (CTR). The CTR of the
opto-coupler varies with initial tolerance, temperature, forward
current, and age.
s
----- = --------------- ? ------- ? ------------------------------------------------
v c N P s s 2
o o
where:
Q = ---------------
(EQ. 26)
ω o = -----------
f o = ------------------
ω z = ----------
f z = ------------------
1
LC
1
R c C
or
or
1
2 π LC
1
2 π R c C
R o = Output Load Resistance
L = Output Inductance
C = Output Capacitance
R c = Output Capacitance ESR
V S = Sawtooth Ramp Amplitude
Gain and phase plots of (Equation 26) appear below using
L = 4.0 μ H, C = 150 μ F, Rc = 28m Ω , Ro = 1.2 Ω , and VIN = 75V.
22
FN9111.6
December 2, 2011
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| ISL6741IV | 功能描述:IC REG CTRLR PWM CM 16-TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:100% 电源电压:8.2 V ~ 30 V 降压:无 升压:无 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:0°C ~ 70°C 封装/外壳:8-DIP（0.300"，7.62mm） 包装:管件 产品目录页面:1316 (CN2011-ZH PDF) |
| ISL6741IV-T | 功能描述:IC REG CTRLR PWM CM 16-TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:100% 电源电压:8.2 V ~ 30 V 降压:无 升压:无 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:0°C ~ 70°C 封装/外壳:8-DIP（0.300"，7.62mm） 包装:管件 产品目录页面:1316 (CN2011-ZH PDF) |
| ISL6741IVZ | 功能描述:IC REG CTRLR PWM CM 16-TSSOP 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) |
| ISL6741IVZ-T | 功能描述:IC REG CTRLR PWM CM 16-TSSOP 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) |
| ISL6742AAZA | 功能描述:IC REG CTRLR PWM CM/VM 16-QSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:75 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.3 V ~ 13.5 V 降压:是 升压:是 回扫:是 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 产品目录页面:1051 (CN2011-ZH PDF) 其它名称:296-2543-5 |
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