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參數(shù)資料
| 型號(hào)： | CS5253B-1GDPR5 |
| 英文描述： | Positive Adjustable Voltage Regulator |
| 中文描述： | 積極可調(diào)電壓穩(wěn)壓器 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大?。?/td> | 93K |
| 代理商： | CS5253B-1GDPR5 |
CS5253B–1
http://onsemi.com
8
Adjustable Operation
This LDO adjustable regulator has an output voltage
range of 1.25 V to 5.0 V. An external resistor divider sets the
output voltage as shown in Figure 20. The regulator’s
voltage sensing error amplifier maintains a fixed 1.25 V
reference between the output pin and the adjust pin.
Figure 20. Typical Application Schematic. The
Resistor Divider Sets V
OUT
, With the Internal
1.260 V Reference Dropped Across R1.
A resistor divider network R1 and R2 causes a fixed
current to flow to ground. This current creates a voltage
across R2 that adds to the 1.25 V across R1 and sets the
overall output voltage. The adjust pin current (typically
50
μ
A) also flows through R2 and adds a small error that
should be taken into account if precise adjustment of V
OUT
is necessary. The output voltage is set according to the
formula:
CS5253B–1
V
CONTROL
V
POWER
V
OUT
V
SENSE
Adjust
R2
R1
5.0 V
3.3 V
2.5 V
@ 3.0 A
VOUT
1.25 V
R1
R2
R1
R2
IADJ
The term I
ADJ
×
R2 represents the error added by the
adjust pin current. R1 is chosen so that the minimum load
current is at least 10 mA. R1 and R2 should be of the same
composition for best tracking over temperature.
While not required, a bypass capacitor connected between
the adjust pin and ground will improve transient response
and ripple rejection. A 0.1
μ
F tantalum capacitor is
recommended for “first cut” design. Value and type may be
varied to optimize performance vs. price.
Other Adjustable Operation Considerations
The CS5253B–1 linear regulator has an absolute
maximum specification of 6.0 V for the voltage difference
between V
POWER
and V
OUT
. However, the IC may be used
to regulate voltages in excess of 6.0 V. The two main
considerations in such a design are the sequencing of power
supplies and short circuit capability.
Power supply sequencing should be such that the
V
CONTROL
supply is brought up coincidentally with or
before the V
POWER
supply. This allows the IC to begin
charging the output capacitor as soon as the V
POWER
to
V
OUT
differential is large enough that the pass transistor
conducts. As V
POWER
increases, the pass transistor will
remain in dropout, and current is passed to the load until
V
OUT
is in regulation. Further increase in the supply voltage
brings the pass transistor out of dropout. In this manner, any
output voltage less than 13 V may be regulated, provided the
V
POWER
to V
OUT
differential is less than 6.0 V. In the case
where V
CONTROL
and V
POWER
are shorted, there is no
theoretical limit to the regulated voltage as long as the
V
POWER
to V
OUT
differential of 6.0 V is not exceeded.
There is a possibility of damaging the IC when V
POWER
– V
OUT
is greater than 6.0 V if a short circuit occurs. Short
circuit conditions will result in the immediate operation of
the pass transistor outside of its safe operating area.
Overvoltage stresses will then cause destruction of the pass
transistor before overcurrent or thermal shutdown circuitry
can become active. Additional circuitry may be required to
clamp the V
POWER
to V
OUT
differential to less than 6.0 V
if fail safe operation is required. One possible clamp circuit
is illustrated in Figure 21; however, the design of clamp
circuitry must be done on an application by application
basis. Care must be taken to ensure the clamp actually
protects the design. Components used in the clamp design
must be able to withstand the short circuit condition
indefinitely while protecting the IC.
Figure 21. This Circuit Is an Example of How the
CS5253B–1 Can Be Short–Circuit Protected When
Operating With V
OUT
> 6.0 V
V
CONTROL
CS5253B–1
V
POWER
V
SENSE
V
OUT
V
ADJ
External Supply
External
Supply
Stability Considerations
The output compensation capacitor helps determine three
main characteristics of a linear regulator: loop stability,
start–up delay, and load transient response. Different
capacitor types vary widely in tolerance, ESR (equivalent
series resistance), ESL (equivalent series inductance), and
variation over temperature. Tantalum and aluminum
electrolytic capacitors work best, with electrolytic
capacitors being less expensive in general, but varying more
in capacitor value and ESR over temperature.
The CS5253B–1 requires an output capacitor to guarantee
loop stability. The Stability vs ESR graph in the typical
performance section shows the minimum ESR needed to
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| CS5253B-1GDPR5G | 制造商:ON Semiconductor 功能描述: |
| CS5253B-8 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:3.0 A LDO 5-Pin 2.5 V Fixed Linear Regulator for Remote Sense Applications |
| CS5253B-8/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:3A LDO 5-Pin 2.5V Fixed Linear Regulatorfor Remote Sense Applications |
| CS5253B-8_05 | 制造商:ONSEMI 制造商全稱:ON Semiconductor 功能描述:3.0 A LDO 5−Pin 2.5 V Fixed Linear Regulator for Remote Sense Applications |
| CS5253B-8GDP5 | 制造商:Rochester Electronics LLC 功能描述:- Bulk 制造商:ON Semiconductor 功能描述:3.0 A LDO 5-Pin 2.5 V Fixed Linear Regulator for Remote Sense Applications |
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