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參數(shù)資料
| 型號： | UC2526DWTR |
| 英文描述： | LOW POWER VOLTAGE REGULATOR |
| 中文描述： | 電壓模式開關(guān)電源控制器 |
| 文件頁數(shù)： | 4/8頁 |
| 文件大?。?/td> | 618K |
| 代理商： | UC2526DWTR |
UC1526
UC2526
UC3526
APPLICATIONS INFORMATION
Voltage Reference
T
he reference regulator of the UC1526 is based on a tem-
perature compensated zener diode. The circuitry is fully
active at supply voltages above +8V, and provides up to
20mA of load current to external circuitry at +5.0V. In sys-
tems where additional current is required, an external
PNP transistor can be used to boost the available current.
A rugged low frequency audio-type transistor should be
used, and lead lengths between the PWM and transistor
should be as short as possible to minimize the risk of os-
cillations. Even so, some types of transistors may require
collector-base capacitance for stability. Up to 1 amp of
load current can be obtained with excellent regulation if
the device selected maintains high current gain.
Under-Voltage Lockout
The under-voltage lockout circuit protects the UC1526
and the power devices it controls from inadequate supply
voltage, If +V
IN
is too low, the circuit disables the output
drivers and holds the RESET
spurious output pulses while the control circuitry is stabi-
lizing, and holds the soft-start timing capacitor in a dis-
charged state.
pin LOW. This prevents
The circuit consists of a +1.2V bandgap reference and
comparator circuit which is active when the reference
voltage has risen to 3V
BE
or +1.8V at 25°C. When the ref-
erence voltage rises to approximately +4.4V, the circuit
enables the output drivers and releases the RESET
allowing a normal soft-start. The comparator has 200mV
of hysteresis to minimize oscillation at the trip point.
When +V
IN
to the PWM is removed and the reference
drops to +4.2V, the under-voltage circuit pulls RESET
LOW again. The soft-start capacitor is immediately dis-
charged, and the PWM is ready for another soft-start cy-
cle.
pin,
The UC1526 can operate from a +5V supply by connect-
ing the V
REF
pin to the +V
IN
pin and maintaining the sup-
ply between +4.8 and +5.2V.
Soft-Start Circuit
The soft-start circuit protects the power transistors and
rectifier diodes from high current surges during power
supply turn-on. When supply voltage is first applied to the
UC1526, the under-voltage lockout circuit holds RESET
LOW with Q
3
. Q
1
is turned on, which holds the soft-start
capacitor voltage at zero. The second collector of Q
1
clamps the output of the error amplifier to ground, guaran-
teeing zero duty cycle at the driver outputs. When the
supply voltage reaches normal operating range, RESET
will go HIGH. Q
1
turns off, allowing the internal 100mA
current source to charge C
S
. Q
2
clamps the error ampli-
fier output to 1V
BE
above the voltage on C
S
. As the soft-
start voltage ramps up to +5V, the duty cycle of the PWM
linearly increases to whatever value the voltage regula-
tion loop requires for an error null.
Digital Control Ports
The three digital control ports of the UC1526 are bi-direc-
tional. Each pin can drive TTL and 5V CMOS logic di-
rectly, up to a fan-out of 10 low-power Schottky gates.
Each pin can also be directly driven by open-collector
Figure 2.
Under-Voltage Lockout Schematic
Figure 1.
Extending Reference Output Current
Figure 3.
Soft-Start Circuit Schematic
4
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相關(guān)PDF資料 |
PDF描述 |
|---|---|
| UC2526J | LOW POWER VOLTAGE REGULATOR |
| UC2526L | Low drop voltage regulator |
| UC2526N | Low drop voltage regulator |
| UC2526Q | Low drop voltage regulator |
| UC2526QTR | 5V, 500mA low drop voltage regulator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| UC2526DWTRG4 | 制造商:Texas Instruments 功能描述:VOLT MODE PWM CNTRLR 100MA 18SOIC - Tape and Reel |
| UC2526J | 制造商:Texas Instruments 功能描述:Voltage Mode PWM Controller 100mA 18-Pin CDIP Tube 制造商:Rochester Electronics LLC 功能描述:REG PULSE WIDTH MOD - Bulk |
| UC2526L | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Mode SMPS Controller |
| UC2526N | 功能描述:電壓模式 PWM 控制器 Regulating Pulse Width Modulator RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| UC2526NG4 | 功能描述:電壓模式 PWM 控制器 Regulating Pulse Width Modulator RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
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