- 您现在的位置：买卖IC网 > PDF目录1809 > IR3637STRPBF (International Rectifier)IC REG CTRLR BUCK PWM VM 8-SOIC PDF资料下载
参数资料
| 型号： | IR3637STRPBF |
| 厂商： | International Rectifier |
| 文件页数： | 5/21页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8-SOIC |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 85% |
| 电源电压： | 4.5 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： | 0°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 标准包装 |
| 配用： | IRPP3637-12A-ND - KIT REF DES 12A 1PH SYNC BUCK IRDC3637-ND - BOARD EVAL SYNC BUCK REGULATOR |
| 其它名称： | IR3637STRPBFDKR |
IR3637SPBF
THEORY OF OPERATION
Soft-Start
The IR3637 has a programmable soft-start to control the
output voltage rise and limit the current surge at the start-
25uA
3V
up. To ensure correct start-up, the soft-start sequence
initiates when the Vc and Vcc rise above their threshold
SS/SD
64uA
Max
HDrv
(3.3V and 4.2V respectively) and generates the Power
On Reset (POR) signal. Soft-start function operates by
POR
sourcing an internal current to charge an external ca-
pacitor to about 3V. Initially, the soft-start function clamps
the E/A’s output of the PWM converter and disables the
short circuit protection. During the power up, the output
starts at zero and voltage at Fb is below 0.4V. The feed-
Comp
0.8V
Fb
25K
25K
Error Amp
LDrv
back UVLO is disabled during this time by injecting a
current (64 μ A) into the Fb. This generates a voltage
about 1.6V (64 μ A × 25K) across the negative input of E/
0.4V
A and positive input of the feedback UVLO comparator
(see Figure 3).
64uA × 25K=1.6V
When SS=0
Feeback
POR
The magnitude of this current is inversely proportional to
the voltage at soft-start pin.
The 20 μ A current source starts to charge up the exter-
nal capacitor. In the mean time, the soft-start voltage
ramps up, the current flowing into Fb pin starts to de-
crease linearly and so does the voltage at the positive
pin of feedback UVLO comparator and the voltage nega-
tive input of E/A.
When the soft-start capacitor is around 1V, the current
flowing into the Fb pin is approximately 32 μ A. The volt-
age at the positive input of the E/A is approximately:
32 μ A × 25K = 0.8V
UVLO Comp
Figure 3 - Soft-start circuit for IR3637.
The output start-up time is the time period when soft-
start capacitor voltage increases from 1V to 2V. The start-
up time will be dependent on the size of the external
soft-start capacitor. The start-up time can be estimated
by:
25 μ A × T START /C SS = 2V-1V
For a given start up time, the soft-start capacitor can be
estimated as:
C SS ? 25 μ A × T START /1V
Output of UVLO
The E/A will start to operate and the output voltage starts
POR
3V
to increase. As the soft-start capacitor voltage contin-
ues to go up, the current flowing into the Fb pin will keep
decreasing. Because the voltage at pin of E/A is regu-
lated to reference voltage 0.8V, the voltage at the Fb is:
V FB = 0.8-25K × (Injected Current)
Soft-Start
Voltage
Current flowing
into Fb pin
0V
64uA
0uA
? 2V
? 1V
The feedback voltage increases linearly as the injecting
current goes down. The injecting current drops to zero
when soft-start voltage is around 2V and the output volt-
age goes into steady state.
Voltage at negative input ? 1.6V
of Error Amp and Feedback
UVLO comparator
0.8V
0.8V
As shown in Figure 4, the positive pin of feedback UVLO
comparator is always higher than 0.4V, therefore, feed-
Voltage at Fb pin
0V
back UVLO is not functional during soft-start.
Figure 4 - Theoretical operational waveforms
during soft-start.
Rev. 1.1
06/16/05
www.irf.com
5
相关PDF资料 |
PDF描述 |
|---|---|
| IR3638STRPBF | IC REG CTRLR BUCK PWM VM 14-SOIC |
| IR3640MPBF | IC REG CTRLR BUCK PWM VM 20-MLPQ |
| IR3651STRPBF | IC REG CTRLR BUCK PWM VM 14-SOIC |
| IR3710MTRPBF | IC REG CTRLR BUCK PWM 16-MLPQ |
| IR3720MTRPBF | IC POWER SUPPLY MONITOR 10-DFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| IR3638 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:High Frequency Synchronous |
| IR3638DR2G | 制造商:ON Semiconductor 功能描述: |
| IR3638SPBF | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGH FREQUENCY SYNCHRONOUS PWM BUCK CONTROLLER FOR TRACKING APPLIACTIONS |
| IR3638STRPBF | 功能描述:电压模式 PWM 控制器 HI FREQ SYNC PWM 400kHz 0.6V Track RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| IR3640MPBF | 功能描述:IC REG CTRLR BUCK PWM VM 20-MLPQ 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:无 工作温度:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
发布紧急采购，3分钟左右您将得到回复。