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参数资料
| 型号： | LT1246CN8 |
| 厂商： | Linear Technology |
| 文件页数： | 7/12页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR ISO PWM CM 8-DIP |
| 标准包装： | 50 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 100% |
| 电源电压： | 11 V ~ 25 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： | 0°C ~ 100°C |
| 封装/外壳： | 8-DIP（0.300"，7.62mm） |
| 包装： | 管件 |
LT1246/LT1247
PI FU C TI
GND (Pin 5): Ground.
S
V REF (Pin 8): Reference. This is the reference output of the
OUTPUT (Pin 6): Current Output. This pin is the output of
a high current totem pole output stage. It is capable of
driving up to ± 1A of current into a capacitive load such as
the gate of a MOSFET.
V CC (Pin 7): Supply Voltage. This pin is the positive supply
of the control IC.
IC. The reference output is used to supply charging current
to the external timing resistor R T . The reference provides
biasing to a large portion of the internal circuitry, and is
used to generate several internal reference levels includ-
ing the V FB level and the current sense clamp voltage.
A PPLICATI
S I FOR ATIO
Minimum
deadtime at that frequency. Curves of oscillator frequency
Device
LT1246
LT1247
Start-Up
Threshold
16V
8.4V
Operating
Voltage
10V
7.6V
Maximum
Duty Cycle
100%
100%
Replaces
UC1842
UC1843
and deadtime for various values of R T and C T appear in the
Typical Performance Characteristics section. Frequency
and deadtime can also be calculated using the following
formulas:
Oscillator Discharge Time: t d =
Oscillator Frequency: f OSC =
Maximum Duty Cycle: D MAX = = OSC d
Oscillator
The LT1246/LT1247 are fixed frequency current mode
pulse width modulators. The oscillator frequency and the
oscillator discharge current are both trimmed and tightly
specified to minimize the variations in frequency and
deadtime. The oscillator frequency is set by choosing a
resistor and capacitor combination, R T and C T . This RC
combination will determine both the frequency and the
maximum duty cycle. The resistor R T is connected from
V REF (pin 8) to the R T /C T pin (pin 4). The capacitor C T is
connected from the R T /C T pin to ground. The charging
current for C T is determined by the value of R T . The
discharge current for C T is set by the difference between
the current supplied by R T and the discharge current of the
LT1246/LT1247. The discharge current of the device is
trimmed to 8.2mA. For large values of R T discharge time
will be determined by the discharge current of the device
and the value of C T . As the value of R T is reduced it will have
more effect on the discharge time of C T . During an oscil-
lator cycle capacitor C T is charged to approximately 2.8V
and discharged to approximately 1.1V. The output is
enabled during the charge time of C T and disabled, in an
off state, during the discharge time of C T . The deadtime of
the circuit is equal to the discharge time of C T . The
maximum duty cycle is limited by controlling the deadtime
of the oscillator. There are many combinations of R T and
C T that will yield a given oscillator frequency, however
there is only one combination that will yield a specific
Oscillator Rise Time: t r = 0.583 ? RC
3 . 46 ? RC
0 . 0164 R ? 11 . 73
Oscillator Period: t OSC = t r + t d
1
t OSC
t r t ? t
t OSC t OSC
The above formulas will give values that will be accurate
to approximately ± 5%, at the oscillator, over the full
operating frequency range. This is due to the fact that the
oscillator trip levels are constant versus frequency and the
discharge current and initial oscillator frequency are
trimmed. Some fine adjustment may be required to achieve
more accurate results. Once the final R T /C T combination is
selected, the oscillator characteristics will be repeatable
from device to device. Note that there will be some slight
differences between maximum duty cycle at the oscillator
and maximum duty cycle at the output due to the finite rise
and fall times of the output.
Error Amplifier
The LT1246/LT1247 contain a fully compensated error
amplifier with a DC gain of 90dB and a unity-gain fre-
quency of 2MHz. Phase margin at unity-gain is 80 ° . The
noninverting input is internally committed to a 2.5V refer-
ence point derived from the 5V reference of pin 8. The
7
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1246CN8#PBF | 功能描述:IC REG CTRLR ISO PWM CM 8-DIP 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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LT1246CS8 | 功能描述:IC REG CTRLR ISO PWM CM 8-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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LT1246CS8#PBF | 功能描述:IC REG CTRLR ISO PWM CM 8-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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LT1246CS8#TR | 功能描述:IC REG CTRLR ISO PWM CM 8-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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LT1246CS8#TRPBF | 功能描述:IC REG CTRLR ISO PWM CM 8-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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
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