- 您现在的位置：买卖IC网 > PDF目录15260 > LTC1698EGN#TR (Linear Technology)IC REG CTRLR ISO PWM CM 16-SSOP PDF资料下载
参数资料
| 型号： | LTC1698EGN#TR |
| 厂商： | Linear Technology |
| 文件页数： | 17/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR ISO PWM CM 16-SSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 400kHz |
| 电源电压： | 6 V ~ 12.6 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： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 其它名称： | LTC1698EGNTR |
LTC1698
APPLICATIO S I FOR ATIO
Once the value of the inductor has been determined, an
inductor with sufficient DC current rating is selected. Core
saturation must be avoided under all operating conditions.
Under start-up conditions, the converter sees a short
circuit while charging the output capacitor. If the inductor
saturates, the peak current will dramatically increase. The
current will be limited only by the primary controller
minimum on time and the circuit impedances.
High efficiency converters generally cannot afford the core
loss found in low cost iron powder cores, forcing the use
of more expensive ferrite, molypermalloy, or Kool M μ ?
cores. As inductance increases, core loss goes down.
Increased inductance requires more turns of wire so
copper losses will increase. The optimum inductor will
have equal core and copper loss.
Ferrite designs have very low core losses and are preferred
at higher switching frequencies. Therefore, design goals
concentrate on minimizing copper loss and preventing
saturation. Kool M μ is a very good, low-loss powder
material with a “soft ” saturation characteristic.
Molypermalloy is more efficient at higher switching fre-
quencies, but is also more expensive. Surface mount
designs are available from many manufacturers using all
of these materials.
Output Capacitor Selection
The output capacitor selection is primarily determined by
the effective series resistance (ESR) to minimize voltage
ripple. In a forward converter application, the inductor
current is constantly flowing to the output capacitor,
therefore, the ripple current at the output capacitor is
small. The output ripple voltage is approximately given by:
Fast load current transitions at the output will appear as a
voltage across the ESR of the output capacitor until the
feedback loop can change the inductor current to match
the new load current value. As an example: at 3.3V out, a
10A load step with a 0.01 ? ESR output capacitor would
experience a 100mV step at the output, a 3% output
change. In surface mount applications, multiple capaci-
tors may have to be placed in parallel to meet the ESR
requirement.
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC1698. These items are also illustrated graphically in
Figure 9. Check the following for your layout:
1. Keep the power circuit and the signal circuit segre-
gated. Place the power circuit, shown in bold, so that
the two MOSFET drain connections are made directly at
the transformer. The two MOSFET sources should be as
close together as possible.
2. Connect PGND directly to the sense resistor with as
short a path as possible. The MOSFET gate drive return
currents flow through this connection.
3. Connect the 4.7 μ F ceramic capacitor directly between
V DD and PGND. This supplies the FG and CG drivers and
must supply the gate drive current.
4. Bypass the V AUX supply with a 0.1 μ F ceramic capacitor
returned to GND.
5. Place all signal components in close proximity to their
associated LTC1698 pins. Return all signal component
grounds directly to the GND pin. One common connec-
V RIPPLE ≈ I RIPPLE ? ? ESR +
8 ? f SW OUT ?
?
?
?
? C
1 ?
tion can be made to V OUT+ from R2, R5 and C CILM .
6. Make the connection between GND and PGND right at
the LTC1698 pins.
The output ripple is highest at maximum input voltage
since I RIPPLE increases with input voltage. Typically, once
the ESR requirement for C OUT has been satisfied the
capacitance is adequate for filtering and has the required
RMS current rating.
7. Use a Kelvin-sense connection from the I SNS and I SNSGND
pins to the secondary-side current-limit resistor
R SECSEN .
Kool M μ is a registered trademark of Magnetics, Inc.
1698f
17
相关PDF资料 |
PDF描述 |
|---|---|
| EYM06DRMD-S273 | CONN EDGECARD 12POS .156 WW |
| LTC1922EG-1#TRPBF | IC REG CTRLR ISO PWM 20-SSOP |
| LTC1698EGN#TRPBF | IC REG CTRLR ISO PWM CM 16-SSOP |
| NCP301LSN46T1G | IC VOLT DETECT OD 4.6V 5TSOP |
| LTC3722EGN-2#TR | IC REG CTRLR DIV ISO PWM 24SSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1698ES | 功能描述:IC REG CTRLR ISO PWM CM 16-SOIC 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:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 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:-40°C ~ 85°C 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC1698ES#PBF | 功能描述:IC REG CTRLR ISO PWM CM 16-SOIC 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:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 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:-40°C ~ 85°C 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC1698ES#TR | 功能描述:IC REG CTRLR ISO PWM CM 16-SOIC 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1698ES#TRPBF | 功能描述:IC REG CTRLR ISO PWM CM 16-SOIC 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1698IGN | 功能描述:IC REG CTRLR ISO PWM CM 16-SSOP 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
发布紧急采购，3分钟左右您将得到回复。