- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄43899 > L4990D (STMICROELECTRONICS) 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16 PDF資料下載
參數(shù)資料
| 型號： | L4990D |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.5 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | SO-16 |
| 文件頁數(shù)： | 4/24頁 |
| 文件大?。?/td> | 322K |
| 代理商： | L4990D |
”Hiccup” keeps the system in control in case of
short circuits but does not eliminate power com-
ponents overstress during pulse-by-pulse limita-
tion (from A to C). Other external protection cir-
cuits are needed if a better control of overloads is
required.
Pin 8. VCC (Controller Supply). This pin supplies
the signal part of the IC. The device is enabled as
VCC voltage exceeds the start threshold and
works as long as the voltage is above the UVLO
threshold. Otherwise the device is shut down and
the current consumption is extremely low.
An internal Zener limits the voltage on VCC to
25V. Below this value the IC current consumption
is low but increases considerably if this limit is ex-
ceeded.
A small film capacitor between this pin and SGND
(pin 12), placed as close as possible to the IC, is
recommended to filter high frequency noise.
Pin 9. VC (Supply of the Power Stage). It sup-
plies the driver of the external switch and there-
fore absorbs a pulsed current. Thus it is recom-
mended to place a buffer capacitor (towards
PGND, pin 11, as close as possible to the IC)
able to sustain these current pulses and in order
to avoid them inducing disturbances.
This pin can be connected to the buffer capacitor
directly or through a resistor, as shown in fig. 25,
to control separately the turn-on and turn-off
speed of the external switch, typically a Power-
MOS. At turn-on the gate resistance is Rg +Rg’
and turn-off is Rg only.
Pin 10. OUT (Driver Output). This pin is the out-
put of the driver stage of the external power
switch. Usually, this will be a PowerMOS, al-
though the driver is powerful enough to drive
BJT’s (1.6A source, 2A sink, peak).
The driver is made up of a totem pole with a high-
side NPN Darlington and a low-side VDMOS, and
delivers a voltage internally clamped, as shown in
fig. 25. Thus it is possible to supply the driver (pin
9) with higher voltages without any problem of
damage for the gate oxide of the external MOS,
but, of course, the power dissipation on the IC will
increase.
In UVLO conditions an internal circuit (shown in
fig.26) holds the pin low in order to ensure that
the external MOS cannot be turned on acciden-
tally. The peculiarity of this circuit is its ability to
mantain the same sink capability (typically, 20mA
@ 1V) from VCC = 0V up to the start-up threshold.
When the threshold is exceeded and the L4990
starts operating, VREFOK is pulled high (refer to
fig. 26) and the circuit is disabled.
It is then possible to omit the ”bleeder” resistor
(connected between the gate and the source of
the MOS) ordinarily used to prevent undesired
switching-on of the external MOS because of
some leakage current.
Pin 11. PGND (Power Ground). The current loop
during the discharge of the gate of the external
MOS is closed through this pin. This loop should
be as short as possible to reduce EMI and run
separately from signal currents return.
Pin 12. SGND (Signal Ground). This ground ref-
erences the control circuitry of the IC, so all the
ground connections of the external parts related
to control functions must lead to this pin. In laying
out the PCB, care must be taken in preventing
switched high currents from flowing through the
SGND path.
Pin 13. ISEN (Current Sense). This pin is to be
connected to the ”hot” lead of the current sense
resistor Rsense (being the other one grounded), to
get a voltage ramp which is an image of the cur-
rent of the switch, (IQ). When this voltage is equal
to:
OUT
Rg
DRIVE &
CONTROL
13V
VC
VCC
Rg’
PGND
Rg(ON)=Rg+Rg’
Rg(OFF)=Rg
D97IN497A
L4990
9
10
11
8
17
13
(V)
Figure25.Turn-on and turn-off speeds adjustment
10
12
SGND
OUT
VREFOK
D97IN538
Figure 26. Pull-Down of the output in UVLO.
L4990 - L4990A
12/24
相關PDF資料 |
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 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| L4991 | 功能描述:TEST COIL FOR REED SWITCH, 1PC RoHS:是 類別:開關 >> 配件 系列:- 標準包裝:100 系列:- 其它名稱: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 制造商全稱:STMicroelectronics 功能描述:Low drop voltage regulator |
| L4993D | 功能描述:低壓差穩(wěn)壓器 - LDO Low drop voltage regulator RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| L4993DTR | 功能描述:低壓差穩(wěn)壓器 - LDO Low drop voltage regulator RoHS:否 制造商:Texas Instruments 最大輸入電壓:36 V 輸出電壓:1.4 V to 20.5 V 回動電壓（最大值）:307 mV 輸出電流:1 A 負載調節(jié):0.3 % 輸出端數(shù)量: 輸出類型:Fixed 最大工作溫度:+ 125 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-20 |
發(fā)布緊急采購，3分鐘左右您將得到回復。