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参数资料
| 型号： | RC1587T |
| 厂商： | FAIRCHILD SEMICONDUCTOR CORP |
| 元件分类： | 可调正电压单路输出LDO稳压器 |
| 英文描述： | 1.5 V-3.6 V ADJUSTABLE POSITIVE LDO REGULATOR, 1.3 V DROPOUT, PSFM3 |
| 封装： | PLASTIC, TO-220, 3 PIN |
| 文件页数： | 15/18页 |
| 文件大小： | 438K |
| 代理商： | RC1587T |
RC1587
PRODUCT SPECIFICATION
6
REV. 1.5.4 3/25/02
Applications Information
General
The RC1587, RC1587-1.5, and RC1587-3.3 are three-terminal
regulators optimized for GTL+ VTT termination applications.
These devices are short-circuit protected, and offer thermal
shutdown to turn off the regulator when the junction temper-
ature exceeds about 150°C. The RC1587 series provides low
dropout voltage and fast transient response. Frequency com-
pensation uses capacitors with low ESR while still maintain-
ing stability. This is critical in addressing the needs of low
voltage high speed microprocessor buses like GTL+.
Stability
The RC1587 series require an output capacitor as a part of
the frequency compensation. It is recommended to use a
22F solid tantalum or a 100F aluminum electrolytic on the
output to ensure stability. The frequency compensation of
these devices optimizes the frequency response with low
ESR capacitors. In general, it is suggested to use capacitors
with an ESR of <300m
. It is also recommended to use
bypass capacitors such as a 22F tantalum or a 100F alumi-
num on the adjust pin of the RC1587 for low ripple and fast
transient response. When these bypassing capacitors are not
used at the adjust pin, larger values of output capacitors pro-
vide equally good results.
Protection Diodes
In normal operation, the RC1587 series does not require any
protection diodes. For the RC1587, internal resistors limit
internal current paths on the adjust pin. Therefore, even with
bypass capacitors on the adjust pin, no protection diode is
needed to ensure device safety under shortcircuit conditions.
A protection diode between the input and output pins is usu-
ally not needed. An internal diode between the input and out-
put pins on the RC1587 series can handle microsecond surge
currents of 50A to 100A. Even with large value output
capacitors it is difcult to obtain those values of surge cur-
rents in normal operation. Only with large values of output
capacitance, such as 1000
F to 5000F, and with the input
pin instantaneously shorted to ground can damage occur. A
crowbar circuit at the input can generate those levels of cur-
rent; a diode from output to input is then recommended, as
shown in Figure 10. Usually, normal power supply cycling or
system “hot plugging and unplugging” will not generate cur-
rent large enough to do any damage.
The adjust pin can be driven on a transient basis
±7V with
respect to the output, without any device degradation. As
with any IC regulator, exceeding the maximum input-to-
output voltage differential causes the internal transistors to
break down and none of the protection circuitry is then
functional.
Figure 10. Optional Protection
Ripple Rejection
In applications that require improved ripple rejection, a
bypass capacitor from the adjust pin of the RC1587 to
ground reduces the output ripple by the ratio of VOUT/1.25V.
The impedance of the adjust pin capacitor at the ripple fre-
quency should be less than the value of R1 (typically in the
range of 100
to 120) in the feedback divider network in
Figure 10. Therefore, the value of the required adjust pin
capacitor is a function of the input ripple frequency. For
example, if R1 equals 100
and the ripple frequency equals
120Hz, the adjust pin capacitor should be 22F. At 10kHz,
only 0.22
F is needed.
Output Voltage
The RC1587 regulator develops a 1.25V reference voltage
between the output pin and the adjust pin (see Figure 11).
Placing a resistor R1 between these two terminals causes a
constant current to ow through R1 and down through R2 to
set the overall output voltage. Normally, this current is the
specied minimum load current of 10mA.
The current out of the adjust pin adds to the current from R1
and is typically 35
A. Its output voltage contribution is
small and only needs consideration when very precise output
voltage setting is required.
RC1587
ADJ
CADJ
R2
R1
65-1587-13
+
C2
22
F
VOUT
+
C1
10
F
+
IN
OUT
D1
1N4002
(OPTIONAL)
VIN
RC1587-1.5, -3.3
GND
C2
22
F
VOUT
C1
10
F
+
IN
OUT
D1
1N4002
(OPTIONAL)
VIN
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相关代理商/技术参数 |
参数描述 |
|---|---|
| RC1587T_32 | 功能描述:低压差稳压器 - LDO 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 |
| RC1587T-1.5 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Positive Fixed Voltage Regulator |
| RC1587T15 | 功能描述:低压差稳压器 - LDO 3A Low Dropout Lin 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 |
| RC1587T15_32 | 功能描述:低压差稳压器 - LDO 3a Lin Reg 1.5V LDO 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 |
| RC1587T15_36 | 功能描述:低压差稳压器 - LDO 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 |
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