参数资料
| 型号： | ISL6742AAZA-T |
| 厂商： | Intersil |
| 文件页数： | 15/18页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM CM/VM 16-QSOP |
| 标准包装： | 1 |
| PWM 型： | 电流/电压模式 |
| 输出数： | 4 |
| 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-SSOP（0.154"，3.90mm 宽） |
| 包装： | 剪切带 (CT) |
| 其它名称： | ISL6742AAZA-TCT |
ISL6742
V IN ? Dt SW
Dt SW ?
R CS = ----------------------------------------------------------------------------------------------------------------------------------
-------- ? ? I O + --------------- ? ? V IN ? ------- S - – V O ? ? + -----------------------------
If Δ V CS is greater than or equal to Ve, then no additional slope
compensation is needed and R CS becomes Equation 22:
N CT
N S ? N ? ?
N P ? 2L O ? N P ? ? L m
(EQ. 22)
If Δ V CS is less than V e , then Equation 19 is still valid for the
value of R CS , but the amount of slope compensation added
by the external ramp must be reduced by Δ V CS .
Adding slope compensation is accomplished in the ISL6742
using an external buffer and the CT signal. A typical
application sums the buffered CT signal with the current
sense feedback and applies the result to the CS pin as
shown in Figure 14.
Example:
V IN = 280V
V O = 12V
L O = 2.0μH
N P /N S = 20
Lm = 2mH
I O = 55A
Oscillator Frequency, F SW = 400kHz
Duty Cycle, D = 85.7%
N CT = 50
R6 = 499 Ω
Solve for the current sense resistor, R CS , using Equation 19.
1
2
3
VREF
ISL6742
16
15
14
R CS = 15.1 Ω .
Determine the amount of voltage, V e , that must be added to
the current feedback signal using Equation 16.
R9
R6
4
5
6
7
8
CT
CS
13
12
11
10
9
V e = 153mV
Next, determine the effect of the magnetizing current from
Equation 21.
Δ V CS = 91mV
Using Equation 24, solve for the summing resistor, R9, from
CT to CS.
R CS
C4
CT
R9 = 13.2k Ω
Determine the new value of R CS , R’ CS , using Equation 25.
R’ CS = 15.7 Ω
FIGURE 14. ADDING SLOPE COMPENSATION
Assuming the designer has selected values for the RC filter
(R6 and C4) placed on the CS pin, the value of R9 required
to add the appropriate external ramp can be found by
superposition.
Additional slope compensation may be considered for
design margin. This discussion determines the minimum
external ramp that is required. The buffer transistor used to
create the external ramp from CT should have a sufficiently
high gain (>200) so as to minimize the required base
current. Whatever base current is required reduces the
V e – Δ V CS = ----------------------
2D ? R6
R6 + R9
V
(EQ. 23)
charging current into CT and will reduce the oscillator
frequency.
Rearranging to solve for R9 yields:
Parallel Operation
Parallel operation of converters using the ISL6742 may be
( 2D – V e + Δ V CS ) ? R6
V e – Δ V CS
R9 = -------------------------------------------------------------
Ω
(EQ. 24)
accomplished using the average current signal, IOUT. IOUT
provides a very accurate representation of the output current
and may be used for active current sharing with many
The value of R CS determined in Equation 19 must be
rescaled so that the current sense signal presented at the
CS pin is that predicted by Equation 17. The divider created
by R6 and R9 makes this necessary.
sharing techniques commonly used including master-slave
and average current sharing methods.
Since IOUT represents the average inductor current (CCM
operation), sharing errors introduced by techniques using
R ′ CS = ---------------------- ? R CS
R6 + R9
R9
15
(EQ. 25)
peak inductor current are reduced. In particular, the current
sharing error introduced by mismatched switching
frequencies is eliminated.
FN9183.2
October 31, 2008
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| ISL6744AABZ | 功能描述:IC REG CTRLR PWM VM 8-SOIC 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) |
| ISL6744AABZ-T | 功能描述:IC REG CTRLR PWM VM 8-SOIC 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) |
| ISL6744AAUZ | 功能描述:IC REG CTRLR PWM VM 8-MSOP 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) |
| ISL6744AAUZ-T | 功能描述:IC REG CTRLR PWM VM 8-MSOP 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) |
| ISL6744AB | 功能描述:电压模式 PWM 控制器 Intermediate Bus 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 |
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