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参数资料
| 型号： | LTC1922EN-1#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR ISO PWM CM/VM 20DIP |
| 标准包装： | 18 |
| PWM 型： | 电流/电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 99% |
| 电源电压： | 3.8 V ~ 10.3 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： | 20-DIP（0.300"，7.62mm） |
| 包装： | 管件 |
LTC1922-1
OPERATIO
φ MOD
CS
PULSE BY PULSE
CURRENT LIMIT
+
–
400mV
PWM
LATCH
Q
S
PWM
LOGIC
UVLO
ENABLE
S Q
R
H = SHUTDOWN
OUTPUTS
Q
OVERLOAD
R CS
CURRENT LIMIT
+
4.1V
12 μ A
600mV
–
S Q
SS
UVLO
ENABLE
R
0.4V
C SS
Q
1922 F08
Figure 8. Current Sense/Fault Circuitry Detail
The pulse-by-pulse comparator has a 400mV nominal
threshold, which can reduce sense resistor losses by 67%
compared to previous solutions. This corresponds to 3W
in a 200W, 48V to 3.3V converter. If the 400mV threshold
is exceeded, the PWM cycle is terminated. The overcurrent
comparator is set approximately 50% higher than the
pulse-by-pulse level. If the current signal exceeds this
level, the PWM cycle is terminated, the soft-start capacitor
is quickly discharged and a soft-start cycle is initiated. If
the overcurrent condition persists, the LTC1922-1 halts
PWM operation and waits for the soft-start capacitor to
charge up to approximately 4V before a retry is allowed.
The soft-start capacitor is charged by an internal 12 μ A
current source. If the fault condition has not cleared when
soft-start reaches 4V, the soft-start pin is again dis-
charged and a new cycle is initiated. This is referred to as
hiccup mode operation. In normal operation and under
most abnormal conditions, the pulse-by-pulse compara-
tor is fast enough to prevent hiccup mode operation. In
severe cases, however, with high input voltage, very low
RDS (ON) MOSFETs and a shorted output, or with saturat-
ing magnetics, the overcurrent comparator provides a
means of protecting the power converter.
Leading Edge Blanking
The LTC1922-1 provides programmable leading edge
circuitry. Although the ZVS full-bridge topology is some-
what more immune to leading edge noise spikes than
other types of converters, they are not totally eliminated.
Leading edge blanking relieves the filtering requirements
for the CS pin, greatly improving the response to real
overcurrent conditions. It also allows the use of a ground
referenced current sense resistor or transformer(s), fur-
ther simplifying the design. With a single 10k to 100k
resistor from R LEB to GND, blanking times of approxi-
mately 40ns to 320ns are programmed. If not required,
connecting R LEB to V REF can disable leading edge blank-
ing. Keep in mind that the use of leading edge blanking will
set a minimum linear control range for the phase modula-
tion circuitry.
Resistive Sensing
A resistor connected between input common and the
sources of MB and MD is the simplest, fastest and most
accurate method of current sensing for the full-bridge
converter. This is the preferred method for low to moder-
ate power levels. A graph of resistive sense power losses
vs output power is shown Figure 9. The sense resistor
should be chosen such that the maximum rated output
current for the converter can be delivered at the lowest
expected V IN . Use the following formula to calculate the
optimal value for R CS .
blanking to prevent nuisance tripping of the current sense
15
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相关代理商/技术参数 |
参数描述 |
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| LTC1922IG-1 | 功能描述:IC REG CTRLR ISO PWM 20-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 |
| LTC1922IG-1#PBF | 功能描述:IC REG CTRLR ISO PWM 20-SSOP 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 |
| LTC1922IG-1#TR | 功能描述:IC REG CTRLR ISO PWM 20-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 |
| LTC1922IG-1#TRPBF | 功能描述:IC REG CTRLR ISO PWM 20-SSOP 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 |
| LTC1922IN-1 | 功能描述:IC REG CTRLR ISO PWM CM/VM 20DIP 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 |
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