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参数资料
| 型号： | LTC1922IG-1#TR |
| 厂商： | Linear Technology |
| 文件页数： | 14/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR ISO PWM 20-SSOP |
| 标准包装： | 1,800 |
| 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-SSOP（0.209"，5.30mm 宽） |
| 包装： | 带卷 (TR) |
LTC1922-1
OPERATIO
2. The LTC1922-1 can either synchronize other PWMs, or
be synchronized to an external frequency source or PWM
chip. See Figure 6 for details.
(33 μ A/V (CT) ). Thus, at the peak of C T , this current is
approximately 125 μ A and is output from the CS pin. A
resistor connected between CS and the external current
C T OF SLAVE(S) IS
1.25 C T OF MASTER.
LTC1922-1
C T
SYNC
1k
5.1k
SYNC
LTC1922-1
C T
C T
sense resistor sums in the required amount of slope
compensation. The value of this resistor is dependent on
several factors including minimum V IN , V OUT , switching
frequency, current sense resistor value and output induc-
C T
MASTER
5.1k
?
1k
SYNC
LTC1922-1
C T
tor value. An illustrative example with the design equation
is provided below.
?
?
UP TO
5 SLAVES
5.1k
SLAVES
C T
1922 F06a
Example: V IN = 36V to 72V
V OUT = 3.3V
Figure 6a. SYNC Output (Master Mode)
AMPLITUDE > 1.8V
I OUT = 40A
L = 2.2 μ H
SYNC
EXTERNAL
FREQUENCY
SOURCE
12.5ns < PW < 0.4/ ?
1k
5.1k
LTC1922-1
C T
C T
Transformer turns ratio (N) = V IN(MIN) ? D MAX /
V OUT = 3
R CS = 0.025 ?
1922 F06b
Figure 6b. SYNC Input from an External Source
3. Slope compensation is required for most peak current
mode controllers in order to prevent subharmonic oscilla-
tion of the current control loop. In general, if the system
f SW = 300kHz, i.e., transformer f = f SW /2 = 150kHz
R SLOPE = V O ? R CS /(2 ? L ? f T ? 125 μ A ? N) = 3.3V ? 0.025/
(2 ? 2.2 μ A ? 100k ? 125 μ A ? 3)
R SLOPE = 500 ? , choose the next higher standard value
to account for tolerances in I SLOPE , R CS , N and L.
V(C T )
duty cycle exceeds 50% in a fixed frequency, continuous
current mode converter, an unstable condition exists
within the current control loop. Any perturbation in the
C T
LTC1922-1
I=
33k
CS
R SLOPE
BRIDGE
CURRENT
current signal is amplified by the PWM modulator result-
ing in an unstable condition. Some common manifesta-
tions of this include alternate pulse nonuniformity and
pulse width jitter. Fortunately, this can be addressed by
33k
ADDED
SLOPE
CURRENT SENSE
WAVEFORM
R CS
1922 F07
adding a corrective slope to the current sense signal or by
subtracting the same slope from the current command
signal (error amplifier output). In theory, the current
doubler output configuration does not require slope com-
pensation since the output inductor duty cycles only
approach 50%. However, transient conditions can mo-
mentarily cause higher duty cycles and therefore, the
possibility for unstable operation. The exact amount of
required slope compensation is easily programmed by the
LTC1922-1 with the addition of a single external resistor
(see Figure 7). The LTC1922-1 generates a current that is
proportional to the instantaneous voltage on C T ,
14
Figure 7. Slope Compensation Circuitry
Current Sensing and Overcurrent Protection
Current sensing provides feedback for the current mode
control loop and protection from overload conditions. The
LTC1922-1 is compatible with either resistive sensing or
current transformer methods. Internally connected to the
LTC1922-1 CS pin are two comparators that provide
pulse-by-pulse and overcurrent shutdown functions re-
spectively. (See Figure 8)
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| 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 |
| LTC1922IN-1#PBF | 功能描述:IC REG CTRLR ISO PWM CM/VM 20DIP 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 |
| LTC1923EGN | 功能描述:IC CONTROLLER TEC HI EFF 28SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 标准包装:1 系列:- 应用:手持/移动设备 电流 - 电源:- 电源电压:3 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-LLP-EP（4x4） 包装:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名称:LP3905SD-30DKR |
| LTC1923EGN#PBF | 功能描述:IC CONTROLLER TEC HI EFF 28SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 电源管理 - 专用 系列:- 标准包装:1 系列:- 应用:手持/移动设备 电流 - 电源:- 电源电压:3 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:14-WFDFN 裸露焊盘 供应商设备封装:14-LLP-EP（4x4） 包装:Digi-Reel® 配用:LP3905SD-30EV-ND - BOARD EVALUATION LP3905SD-30 其它名称:LP3905SD-30DKR |
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