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參數(shù)資料
| 型號： | L4964 |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 4 A SWITCHING REGULATOR, 120 kHz SWITCHING FREQ-MAX, PZFM15 |
| 封裝： | VERTICAL, PLASTIC, MULTIWATT-15 |
| 文件頁數(shù)： | 7/13頁 |
| 文件大?。?/td> | 1058K |
| 代理商： | L4964 |
CIRCUIT OPERATION (refer to the block diagram)
The L4964 is a monolithic stepdown switching regu-
lator providing output voltages from 5.1 V to 28 V
and delivering 4A.
The regulation loop consists of a sawtooth oscillator,
error amplifier, comparator and the output stage. An
error signal is produced by comparing the output
voltage with a precise 5.1 V on-chip reference
(zener zap trimmed to
± 3 %). This error signal is
then compared with the sawtooth signal to generate
the fixed frequency pulse width modulated pulses
which drive the output stage. The gain and fre-
quency stability of the loop can be ajusted by an ex-
ternal RC network connected to pin 9. Closing the
loop directly gives an output voltage of 5.1 V. Higher
voltages are obtained by inserting a voltage divider.
Output overcurrents at switch on are prevented by
the soft start function. The error amplifier output is
initially clamped by the external capacitor Css and al-
lowed to rise, linearly, as this capacitor is charged
by a constant current source.
Output overload protection is provided in the form of
a current limiter. The load current is sensed by an
internal metal resistor connected to a comparator.
When the load current exceeds a preset threshold
this comparator sets a flip flop which disables the
output stage and discharges the soft start capacitor.
A second comparator resets the flip flop when the
voltage across the soft start capacitor has fallen to
0.4 V. The output stage is thus re-enable and the
output voltage rises under contro of the soft start net-
work. If the overload condition is still present the
limiter will trigger again when the thershold current
is reached. The average short circuit current is lim-
ited to a safe value by the dead time introduced by
the soft start network.
The reset circuit generates an output signal when
the supply voltage exceeds a threshold pro-
grammed by an external divider. The reset signal is
generated with a delay time programmed by an ex-
ternal capacitor. When the supply falls below the
threshold the reset output goes low immediately.
The reset output is an open collector.
A TTL - level input is provided for applications such
as remote on/off control. This input is activated by
high level and disables circuit operation. After an in-
hibit the L4964 restarts under control of the soft start
network.
The thermal overload circuit disables circuit opera-
tion when the junction temperature reaches about
150 and has hysteresis to prevent unstable condi-
tions.
Figure 1 : Reset Output Waveforms
L4964
3/13
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| L4964_03 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:HIGH CURRENT SWITCHING REGULATOR |
| L4964HT | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 5.1 to 28V 4.0 Amp 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 |
| L4969 | 功能描述:低壓差穩(wěn)壓器 - LDO Triple w/Lo-Spd Tran 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(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| L4969013TR | 功能描述:低壓差穩(wěn)壓器 - LDO Triple w/Lo-Spd Tran 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(diào)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(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-20 |
| L4969D | 功能描述:線性穩(wěn)壓器 - 標準 Triple w/Lo-Spd Tran RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L |
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