參數(shù)資料
型號(hào)： SP6641A
英文描述： 500mA Alkaline DC/DC Boost Regulator in SOT-23
中文描述： 堿性500mA的DC / DC升壓穩(wěn)壓器采用SOT - 23
文件頁(yè)數(shù)： 7/13頁(yè)
文件大?。?/td> 120K
代理商： SP6641A
7
Rev. 3/5/02, *Patent Pending
SP6641A/6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
Copyright 2002 Sipex Corporation
The SP6641 feed forward off-time control de-
livers more load current than constant off-time
control because the input battery voltage drops
during its life cycle. The term (I
PK
– K
OFF
/2L) is
the average current delivered to the output ca-
pacitor during the discharge phase. This is con-
stant with respect to input and output voltage.
With constant off-time control, the average dis-
charge current term becomes
(I
PK
-T
OFF
*(V
OUT
-V
IN
)/2L),
which decreases as the input voltage drops.
Table 1 illustrates the average inductor current
delivered to the load during discharge versus the
input voltage. The SP6641 feed forward off-
time control and the constant off-time control
are compared. For purposes of illustration, the
off times of each control scheme are normalized
at a typical two cell alkaline input voltage of
2.6V. The values used in Table 1 are:
I
PK
= 0.33A
L = 22
μ
H
V
OUT
= 3.3V
T
OFF
(SP6641) = 1.5V*
μ
s/(3.3-V
IN
)
T
OFF
(constant) = 2.14
μ
s
SP6641A
T
OFF
5.00
μ
s
2.14
μ
s
1.15
μ
s
0.75
μ
s
0.65
μ
s
Constant T
OFF
T
OFF
2.14
μ
s
2.14
μ
s
2.14
μ
s
2.14
μ
s
2.14
μ
s
V
IN
3.0
2.6
2.0
1.3
1.0
Avg I
L
0.30A
0.30A
0.30A
0.30A
0.30A
Avg I
L
0.32A
0.30A
0.27A
0.23A
0.22A
Table 1- Average I
L
vs. Input Voltage
The following equation defines the burst mode
frequency under heavy load conditions:
F
BURST
=
(
K
OFF
V
OUT
+ V
D
–V
C
where:
V
D
= Forward schottky drop, (0.4V, typ)
V
C
= Average charging switch drop,
Rnmos*I
PK
, typically 0.1V
Ignoring the conduction losses of V
D
and V
C
,
the burst frequency equation simplifies to:
F
BURST
= (V
OUT
– V
IN
)V
IN
K
OFF
V
OUT
Startup
The internal regulator circuitry is bootstrapped
to the V
OUT
pin. This requires a low voltage
oscillator and charging switch powered from the
V
BATT
pin to pump up the output voltage until
the reference is established. The reference pro-
vides a REFREADY signal that determines when
output control is handed over to the regulator.
REFREADY shuts down the startup circuit and
enables the regulator when the reference is valid
and V
OUT
is above +1.9V. Once the regulator is
given control it will continue to pump up the
output at full power until regulation is reached.
For two cell alkaline input voltages and above,
the output voltage will be pulled above +1.9V
quickly through the rectifying diode before the
reference has a chance to establish. In this sce-
nario the startup circuit will coarsely regulate
around +2.8V until the REFREADY signal as-
serts. This keeps the output from overshooting
in startup with higher input voltages.
Startup is guaranteed at +0.9V at room tempera-
ture with a 3k
load. Heavier loads will require
a higher input voltage.
Shutdown/Enable Control
Pin 4 of the device is a V
BATT
referred control
pin that shuts down the converter with the pin
tied to ground, or enables the converter with the
pin tied to V
BATT
. When the converter is shut-
down the power switch is opened and all circuit
biasing is extinguished leaving only junction leak-
age currents on supply pins 3 and 5. The output
voltage will droop to one diode drop below the
battery voltage through the rectifying diode.
After pin 4 is brought high, the startup circuit is
enabled and starts pumping up the output until
REFREADY hands over control to the internal
regulator.
OPERATION
Loop Regulation: continued
V
OUT
– V
IN
V
IN
– V
C
)
相關(guān)PDF資料
PDF描述
SP6641B 500mA Alkaline DC/DC Boost Regulator in SOT-23
sp6641 500mA Alkaline DC/DC Boost Regulator in SOT-23(500mA堿性DC/DC升壓穩(wěn)壓器(SOT-23封裝))
SP6641AEK-33TR Circular Connector; No. of Contacts:3; Series:MS27466; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:9; Circular Contact Gender:Socket; Circular Shell Style:Wall Mount Receptacle; Insert Arrangement:9-98 RoHS Compliant: No
SP6641AEK-50TR 500mA Alkaline DC/DC Boost Regulator in SOT-23
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
SP6641A_05 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:500mA Alkaline DC/DC Boost Regulator in SOT-23
SP6641AEK-3.3 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:Low Noise Evaluation Board
SP6641AEK-3.3/TR 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:500mA Alkaline DC/DC Boost Regulator in SOT-23
SP6641AEK-3-3/TR 功能描述:開(kāi)關(guān)變換器、穩(wěn)壓器與控制器 100mA Alkaline DC/DC RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開(kāi)關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel
SP6641AEK-33TR 制造商:SIPEX 制造商全稱(chēng):Sipex Corporation 功能描述:500mA Alkaline DC/DC Boost Regulator in SOT-23
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