- 您现在的位置：买卖IC网 > PDF目录15196 > ISL8843MBZ (Intersil)IC REG CTRLR BST FLYBK ISO 8SOIC PDF资料下载
参数资料
| 型号： | ISL8843MBZ |
| 厂商： | Intersil |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK ISO 8SOIC |
| 标准包装： | 980 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 2MHz |
| 占空比： | 100% |
| 电源电压： | 9 V ~ 30 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： | 是 |
| 工作温度： | -55°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
ISL8843
Q = -------------------------------------------------
1
R CS = ---------------------------------------------------------------------------------------------------------------------------------------------------------
D ? T sw ? V IN ? -- π - + 0.5
?
( 1 – D ) ? V O ? T sw ?
--------------------------------- ? ? ------------------ – 1 ? + ------ s - ? ? I O + ---------------------------------------------- ?
L p
N p ?
2L s
? 1 – D ?
? ?
frequency. The double-pole will be critically damped if the
Q-factor is set to 1, over-damped for Q < 1, and under-
damped for Q > 1. An under-damped condition may result in
current loop instability.
(EQ. 9)
π ( m c ( 1 – D ) – 0.5 )
Substituting Equations 12 and 13 into Equation 14 and
solving for R CS yields
1
1
N ?
?
(EQ. 15)
where D is the percent of on time during a switching cycle.
Setting Q = 1 and solving for Se yields
Adding slope compensation is accomplished in the ISL8843
S e = S n ? ? --- + 0.5 ? ------------- – 1 ?
? ? π ? 1 – D ?
1 1
(EQ. 10)
using an external buffer transistor and the RTCT signal. A
typical application sums the buffered RTCT signal with the
current sense feedback and applies the result to the CS pin
Since Sn and Se are the on time slopes of the current ramp
and the external ramp, respectively, they can be multiplied
by Ton to obtain the voltage change that occurs during Ton.
as shown in Figure 6.
V e = V n ? ? 1 --- + 0.5 ? ------------- – 1 ?
? ? π ? 1 – D ?
1
(EQ. 11)
VREF
where Vn is the change in the current feedback signal ( ? I)
during the on time and Ve is the voltage that must be added
R9
by the external ramp.
For a flyback converter, Vn can be solved for in terms of
R6
CS
input voltage, current transducer components, and primary
inductance, yielding
C4
RTCT
V e = ---------------------------------------------------- ? ? --- + 0.5 ? ------------- – 1 ?
D ? T SW ? V IN ? R CS 1 1
L p ? ? π ? 1 – D ?
V
(EQ. 12)
FIGURE 6. SLOPE COMPENSATION
where R CS is the current sense resistor, T SW is the
switching frequency, L p is the primary inductance, V IN is the
minimum input voltage, and D is the maximum duty cycle.
The current sense signal at the end of the ON time for CCM
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.
V CS = ------------------------ ? I O + ---------------------------------------------- ?
V e = ---------------------------- V
operation is:
N P ? 2L s ?
N S ? R CS ? ( 1 – D ) ? V O ? T sw ?
V
(EQ. 13)
(EQ. 16)
R6 + R9
The factor of 2.05 in Equation 16 arises from the peak
amplitude of the sawtooth waveform on RTCT minus a base-
where V CS is the voltage across the current sense resistor,
L s is the secondary winding inductance, and I O is the output
current at current limit. Equation 13 assumes the voltage
emitter junction drop. That voltage multiplied by the
maximum duty cycle is the voltage source for the slope
compensation. Rearranging to solve for R9 yields:
( 2.05D – V e ) ? R6
drop across the output rectifier is negligible.
Since the peak current limit threshold is 1.00V, the total
current feedback signal plus the external ramp voltage must
R9 = -----------------------------------------------
V e
?
(EQ. 17)
sum to this value when the output load is at the current limit
threshold.
The value of R CS determined in Equation 15 must be
rescaled so that the current sense signal presented at the
CS pin is that predicted by Equation 13. The divider created
V e + V CS = 1
(EQ. 14)
by R6 and R9 makes this necessary.
R ′ CS = ---------------------- ? R CS
9
R6 + R9
R9
(EQ. 18)
FN9238.1
January 3, 2006
相关PDF资料 |
PDF描述 |
|---|---|
| ACC17DREF | CONN EDGECARD 34POS .100 EYELET |
| VE-J4P-EW-F4 | CONVERTER MOD DC/DC 13.8V 100W |
| B41042A5108M | 1000UF 25V 12.5X25 SINGLE END |
| ISL8843AUZ | IC REG CTRLR BST FLYBK ISO 8MSOP |
| B41041A8108M | 1000UF 63V 16X31.5 SINGLE END |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL8843MBZ-T | 功能描述:IC REG CTRLR BST FLYBK ISO 8SOIC 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) |
| ISL8843MUZ | 功能描述:IC REG CTRLR BST FLYBK ISO 8MSOP 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) |
| ISL8843MUZ-T | 功能描述:IC REG CTRLR BST FLYBK ISO 8MSOP 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) |
| ISL8844AABZ | 功能描述:IC REG CTRLR BST FLYBK ISO 8SOIC 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) |
| ISL8844AABZ-T | 功能描述:IC REG CTRLR BST FLYBK ISO 8SOIC 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) |
发布紧急采购，3分钟左右您将得到回复。