- 您现在的位置：买卖IC网 > PDF目录43899 > L4990D (STMICROELECTRONICS) 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16 PDF资料下载
参数资料
| 型号： | L4990D |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 稳压器 |
| 英文描述： | 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | SO-16 |
| 文件页数： | 3/24页 |
| 文件大小： | 322K |
| 代理商： | L4990D |
Tss
3
Rsense IQpk
ISSC
Css
(6)
where Rsense is the current sense resistor (see pin
13) and IQpk is the switch peak current (flowing
through Rsense), which depends on the output
load. Usually, CSS is selected for a TSS in the or-
der of milliseconds.
As mentioned before, the soft-start intervenes
also in case of severe overload or short circuit on
the output. Referring to fig. 23, pulse-by-pulse
current limitation is somehow effective as long as
the ON-time of the power switch can be reduced
(from A to B). After the minimum ON-time is
reached (from B onwards) the current is out of
control.
To prevent this risk, a comparator trips an over-
current handling procedure, named ’hiccup’ mode
operation, when a voltage above 1.2V (point C) is
detected on current sense input (ISEN, pin 13).
Basically, the IC is turned off and then soft-started
as long as the fault condition is detected. As a re-
sult, the operating point is moved abruptly to D,
creating a foldback effect. Fig. 24 illustrates the
operation.
The oscillation frequency appearing on the soft-
start capacitor in case of permanent fault, referred
to as ’hiccup” period, is approximately given by:
Thic 4.5
1
ISSC
+
1
ISSD
Css (7)
Since the system tries restarting each hiccup cy-
cle, there is not any latchoff risk.
VOUT
TON
D.C.M.
C.C.M.
D
A
B
C
IQpk
TON(min)
1-2 IQpk
IQpk(max)
IOUT
ISHORT IOUT(max)
D97IN495
Figure 23. Regulation characteristic and re-
lated quantities
7V
Thic
time
SHORT
IOUT
ISEN
FAULT
SS
5V
0.5V
D97IN496
Figure 24. Hiccup mode operation.
L4990 - L4990A
11/24
相关PDF资料 |
PDF描述 |
|---|---|
| L5970AD | 1.8 A SWITCHING REGULATOR, 500 kHz SWITCHING FREQ-MAX, PDSO8 |
| L5972D013TR | 3 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO8 |
| L5972D | 3 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO8 |
| L5973AD | 2.3 A SWITCHING REGULATOR, PDSO8 |
| L5973D | 3.5 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO8 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| L4991 | 功能描述:TEST COIL FOR REED SWITCH, 1PC RoHS:是 类别:开关 >> 配件 系列:- 标准包装:100 系列:- 其它名称:886.0007886.0007-ND |
| L4992 | 制造商:STMicroelectronics 功能描述: 制造商:STMicroelectronics 功能描述:VOLT SUPERVISOR CNTRLR 5.1V/3.3V 32TQFP - Trays |
| L4993 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:Low drop voltage regulator |
| L4993D | 功能描述:低压差稳压器 - LDO Low drop voltage regulator RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| L4993DTR | 功能描述:低压差稳压器 - LDO Low drop voltage regulator RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
发布紧急采购，3分钟左右您将得到回复。