Datasheet > AS2954AN-3.3

AS2954AN-3.3

更新时间： 2024-01-22 02:11:50

品牌	Logo	应用领域
西伯斯 - SIPEX		/
页数	文件大小	规格书
6页	182K
描述
Fixed Positive LDO Regulator, 3.3V, 0.6V Dropout, PBCY3, TO-92, 3 PIN

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技术参数
数据手册

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AS2954AN-3.3 技术参数

是否Rohs认证：	不符合	生命周期：	Obsolete
包装说明：	TO-92, 3 PIN	Reach Compliance Code：	unknown
风险等级：	5.75	Is Samacsys：	N
最大回动电压 1：	0.6 V	最大输入电压：	30 V
最小输入电压：	6 V	JESD-30 代码：	O-PBCY-T3
湿度敏感等级：	1	功能数量：	1
端子数量：	3	工作温度TJ-Max：	125 °C
工作温度TJ-Min：	-40 °C	最大输出电流 1：	0.25 A
最大输出电压 1：	3.35 V	最小输出电压 1：	3.251 V
标称输出电压 1：	3.3 V	封装主体材料：	PLASTIC/EPOXY
封装代码：	TO-92	封装形状：	ROUND
封装形式：	CYLINDRICAL	峰值回流温度（摄氏度）：	225
认证状态：	Not Qualified	调节器类型：	FIXED POSITIVE SINGLE OUTPUT LDO REGULATOR
表面贴装：	NO	端子形式：	THROUGH-HOLE
端子位置：	BOTTOM	处于峰值回流温度下的最长时间：	NOT SPECIFIED
Base Number Matches：	1

AS2954AN-3.3 数据手册

AS2954

APPLICATION HINTS

EXTERNAL CAPACITORS

This problem can be fixed by adding a 100pF capacitor between

output and feedback and increasing the output capacitor to at least

3.3µF.

For the stability of the AS2954 requires a 2.2µF or greater

capacitor between output and ground. Oscillation could occur

without this capacitor. Most types of tantalum or aluminum

electrolytic works fine here. For operations of below -25°C solid

tantalum is recommended since the many aluminum types have

electrolytes the freeze at about -30°C. The ESR of about 5Ω or

less and resonant frequency above 500kHz are the most

important parameters in the value of the capacitor. The capacitor

value can be increased without limit.

ERROR DETECTION COMPARATOR OUTPUT

The Comparator produces a logic low output whenever the AS2954

output falls out of regulation by more than around 5%. This is around

60mV offset divided by the 1.235 reference voltage. This trip level

remains 5% below normal regardless of the programmed output

voltage of the regulator. Figure 1 shows the timing diagram depicting

the ERROR signal and the regulator output voltage as the AS2954

input is ramped up and down. The ERROR signal becomes low at

around 1.3V input, and goes high around 5V input (input voltage at

which V_OUT= 4.75. Since the AS2954’s dropout voltage is load

dependent, the input voltage trip point (around 5V) will vary with the

load current. The output voltage trip point (approx. 4.75V) does not

vary with load.

At lower values of output current, less output capacitance is

required for stability. For the currents below 10mA the value of

the capacitor can be reduced to 0.5µF and 0.15µF for 1mA.

More output capacitance needed for the 8-pin version at voltages

below 5V since it runs the error amplifier at lower gain. At worst

case 5µF or greater must be used for the condition of 250mA

load at 1.23V output.

The error comparator has an open-collector output, which requires an

external pull-up resistor. Depending on the system requirements the

resistor may be returned to 5V output or other supply voltage. In

determining the value of this resistor, note that the output is rated to

sink 400µA, this value adds to battery drain in a low battery

condition. Suggested values range from 100K to 1MΩ. If the output

is unused this resistor is not required.

The AS2954, unlike other low dropout regulators will remain

stable and in regulation with no load in addition to the internal

voltage divider.

This feature is especially important in

application like CMOS RAM keep-alive. When setting the

output voltage of the AS2954, a minimum load of 1µA is

recommended

If there is more than 10 inches of wire between the input and the

AC filter capacitor or if a battery is used as the input then a 1µA

tantalum or aluminum electrolytic capacitor should be placed

from the input to the ground.

PROGRAMMING THE OUTPUT VOLTAGE OF AS2954

The AS2954 may be pin-strapped for 5V using its internal voltage

divider by tying Pin 1 (output) to Pin 2 (sense) and Pin 7 (feedback)

to Pin 6 (5V Tap).

Instability can occur if there is stray capacitance to the AS2954

feedback terminal (pin 7). This could cause more problems when

using a higher value of external resistors to set the output voltage.

+V_IN

4.75V

100K

OUTPUT

+V_IN

______

ERROR

VOLTAGE

ERROR

1.2 to 30V

OUTPUT

V_OUT

_______

ERROR*

AS2954

R₁

SHUTDOWN

INPUT

3.3uF

.01uF

GND

5.0V

1.23V

V _REF

INPUT

1.3V

VOLTAGE

R₂

* See Application Info

_______

Figure 1. ERROR Output Timing

Figure 2. Adjustable Regulator

Rev.9/29/00

1 2 345 6

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与AS2954AN-3.3相关器件

型号	品牌	描述	获取价格	数据表
AS2954AN5.0	CALOGIC	Fixed Positive LDO Regulator, 5V, 0.6V Dropout, PBCY3, TO-92, 3 PIN	获取价格
AS2954AN-5.0	SIPEX	Fixed Positive LDO Regulator, 5V, 0.6V Dropout, PBCY3, TO-92, 3 PIN	获取价格
AS2954AN5.0OPTION1	CALOGIC	Fixed Positive LDO Regulator, 5V, 0.6V Dropout, PBCY3, TO-92, 3 PIN	获取价格
AS2954AN5.0OPTION2	CALOGIC	Fixed Positive LDO Regulator, 5V, 0.6V Dropout, PBCY3, TO-92, 3 PIN	获取价格
AS2954AN5.0OPTION3	CALOGIC	Fixed Positive LDO Regulator, 5V, 0.6V Dropout, PBCY3, TO-92, 3 PIN	获取价格
AS2954AN5.0OPTION4	CALOGIC	Fixed Positive LDO Regulator, 5V, 0.6V Dropout, PBCY3, TO-92, 3 PIN	获取价格

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