- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄97994 > L4977A (STMICROELECTRONICS) 11 A SWITCHING REGULATOR, 500 kHz SWITCHING FREQ-MAX, PZFM15 PDF資料下載
參數(shù)資料
| 型號： | L4977A |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 11 A SWITCHING REGULATOR, 500 kHz SWITCHING FREQ-MAX, PZFM15 |
| 封裝： | PLASTIC, POWER PACK-15 |
| 文件頁數(shù)： | 15/21頁 |
| 文件大?。?/td> | 6754K |
| 代理商： | L4977A |
CIRCUIT OPERATION (refer to the block dia-
gram)
The L4977A is a 7A monolithic stepdown switching
regulator working in continuous mode realized in
the new BCD Technology. This technology allows
the integration of isolated vertical DMOS power
transistors plus mixed CMOS/Bipolar transistors.
The device can deliver 7A at an output voltage
adjustable from 5.1V to 40V, and contains diag-
nostic and control functions that make it particu-
larly suitable for microprocessor based systems.
BLOCK DIAGRAM
The block diagram shows the DMOS power tran-
sistor and the PWM control loop. Integrated func-
tions include a reference voltage trimmed to 5.1V
± 2%, soft start, undervoltage lockout, oscillator
with feedforward control, pulse by pulse current
limit, thermal shutdown and finally the reset and
power fail circuit. The reset and power fail circuit
provides an output signal for a microprocessor in-
dicating the status of the system.
Device turn on is around 11V with a typical 1V
hysteresis, this threshold provides a correct volt-
age for the driving stage of the DMOS gate and
the hysteresis prevents instabilities.
An external bootstrap capacitor charged to 12V
by an internal voltage reference is needed to pro-
vide correct gate drive to the power DMOS. The
driving circuit is able to source and sink peak cur-
rents of around 0.5A to the gate of the DMOS
transistor. A typical switching time of the current
in the DMOS transistor is 50ns. Due to the fast
commutation switching frequencies up to 500kHz
are possible.
The PWM control loop consists of a sawtooth os-
cillator, error amplifier, comparator, latch and the
output stage. An error signal is produced by com-
paring the output voltage with the precise 5.1V
±
2% on chip reference. This error signal is then
compared with the sawtooth oscillator, in order to
generate a fixed frequency pulse width modulated
drive for the output stage. A PWM latch is in-
cluded to eliminate multiple pulsing within a pe-
riod even in noisy environments. The gain and
PIN FUNCTIONS
N
o
Name
Function
1
OSCILLATOR
Rosc. External resistor connected to ground determines the constant charging
current of Cosc.
2
OSCILLATOR
Cosc. External capacitor connected to ground determines (with Rosc) the
switching frequency.
3
RESET INPUT
Input of Power Fail Circuit. The threshold is 5.1V. It may be connected via a
divider to the input for power fail function. It must be connected to the pin 14 an
external 30K
resistor when power fail signal not required.
4
RESET OUT
Open Collector Reset/power Fail Signal Output. This output is high when the
supply and the output voltages are safe.
5
RESET DELAY
A Cd capacitor connected between this terminal and ground determines the
reset signal delay time.
6
BOOTSTRAP
A Cboot capacitor connected between this terminal and the output allows to
drive properly the internal D-MOS transistor.
7
OUTPUT
Regulator Output.
8
GROUND
Common Ground Terminal
9
SUPPLY VOLTAGE
Unregulated Input Voltage.
10
FREQUENCY
COMPENSATION
A series RC network connected between this terminal and ground determines
the regulation loop gain characteristics.
11
FEEDBACK INPUT
The Feedback Terminal of the Regulation Loop. The output is connected
directly to this terminal for 5.1V operation; It is connected via a divider for higher
voltages.
12
SOFT START
Soft Start Time Constant. A capacitor is connected between thi sterminal and
ground to define the soft start time constant.
13
SYNC INPUT
Multiple L4977A are synchronized by connecting pin 13 inputs together or via
an external syncr. pulse.
14
Vref
5.1V Vref Device Reference Voltage.
15
Vstart
Internal Start-up Circuit to Drive the Power Stage.
L4977A
3/21
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| L4978D013TR | 3.5 A SWITCHING REGULATOR, 300 kHz SWITCHING FREQ-MAX, PDSO16 |
| L4978 | 3.5 A SWITCHING REGULATOR, 300 kHz SWITCHING FREQ-MAX, PDIP8 |
| L497B | SPECIALTY ANALOG CIRCUIT, PDIP16 |
| L4981BD013TR | 2 A POWER FACTOR CONTROLLER, 115 kHz SWITCHING FREQ-MAX, PDSO20 |
| L4985D | 1.5 A SWITCHING REGULATOR, 83 kHz SWITCHING FREQ-MAX, PDSO20 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| L4977HT | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Mode SMPS Controller |
| L4978 | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3.3 to 50V Step-Down RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| L4978_05 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:2A STEP DOWN SWITCHING REGULATOR |
| L4978D | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3.3 to 50V Step-Down RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| L4978D013TR | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3.3 to 50V Step-Down RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。