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PDF AIC1845 Data sheet ( Hoja de datos )
| Número de pieza | AIC1845 | |
| Descripción | Regulated 5V Charge Pump In SOT-23 | |
| Fabricantes | Analog Integrations | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AIC1845 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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heet4U.comFEATURES
taSUltralow Power: IIN = 13µA
aRegulated 5V ±4% Output Voltage
.DOutput Current: 100mA (VIN =3.3V)
w 110mA (VIN =3.6V)
wwInput Range: 2.7V to 5.0V
AIC1845
Regulated 5V Charge Pump In SOT-23
DESCRIPTION
The AIC1845 is a micropower charge pump
DC/DC converter that produces a regulated 5V
output. The input voltage range is 2.7V to 5.0V.
Extremely low operating current (13µA typical
with no load) and a low external-part count (one
No Inductors Needed
Very Low Shutdown Current: <1µA
mInternal Oscillator: 650KHz
Short-Circuit and Overtemperature Protection
o6-Pin SOT-23 Package
U.cAPPLICATIONS
t4White or Blue LED Backlighting
SIM Interface Supplies for Cellular Telephones
eLi-Ion Battery Backup Supplies
Local 3V to 5V Conversion
eSmart Card Readers
hPCMCIA Local 5V Supplies
0.22µF flying capacitor and two small bypass
capacitors at VIN and VOUT ) make the AIC1845
ideally suitable for small, battery-powered
applications.
The AIC1845 operates as a PSM (Pulse
Skipping Modulation) mode switched capacitor
voltage doubler to produce a regulated output
and features with thermal shutdown capability
and short circuit protection.
The AIC1845 is available in a 6-pin SOT-23
package.
taSTYPICAL APPLICATION CIRCUIT
.Da1-Cell
wwwLi-ion Battery
CIN
2.2µF
U1
1 VOUT
2 GND
3
SHDN
C+ 6
VIN 5
C- 4
AIC1845
VOUT
** R1
COUT
2.2µF
* ** *
0.22µF
CFLY
Regulated 5V Output from 2.7V to 5.0V Input
om* WLED series number: NSPW310BS, VF=3.6V, IF=20mA
t4U.c**
R1 =
VOUT − VF
IF × NWLED
, NWLED:
The
number of WLED
eCIN, COUT: CELMK212BJ225MG (X5R) (0805), TAIYO YUDEN
heCFLY : CEEMK212BJ224KG (X7R) (0805), TAIYO YUDEN
www.DataSAnalog Integrations Corporation
Si-Soft Research Center
3A1, No.1, Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan, R.O.C.
TEL: 886-3-5772500
FAX: 886-3-5772510 www.analog.com.tw
DS-1845P-03 010405
1
1 page  
AIC1845
TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
50
45
40
35
VIN=3.6V
30
25
20 VIN=3.3V
15 VIN=3.0V
10
5
VIN=2.7V
COUT=10µF
CFLY=1µF
0 0 20 40 60 80 100 120 140
Output Current (mA)
Fig.7 Output Current vs. Output Ripple
175
150
125
100
75
50
25
0
0
VIN=3.6V
VIN=3.3V
VIN=3.0V
VIN=2.7V
COUT=2.2µF
CFLY=0.22µF
20 40 60 80 100 120
Output Current (mA)
Fig. 8 Output Current vs. Output Ripple
140
1000
900
VIN=2.5V
800
700
600
500
400-60 -40 -20
0 20 40 60 80 100 120 140
Temperature (°C)
Fig. 9 Frequency vs. Temperature
280
260 TA=25°C
240 CFLY=1µF
220
200
180
160
140
120
1002.5
3.0 3.5 4.0 4.5
Supply Voltage (V)
5.0
Fig. 11 Short-Circuit Current vs. Supply Voltage
5.05
5.00
VIN=3.0V
CFLY=1µF
4.95 IOUT=50mA
4.90
4.85
-60
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
Fig. 10 Output Voltage vs. Temperature
140
220
200
180
160
140
120 TA=25°C
100 CFLY=0.22µF
2.5 3.0 3.5 4.0 4.5 5.0 5.5
Supply Voltage (V)
Fig. 12 Short-Circuit Current vs. Supply Voltage
5
5 Page 
AIC1845
∆Q = QON - QOFF
= C1 × (VC1−ON−AVE − VC1−OFF−AVE )
= C1 × (2VIN - VOUT - 2RDS-ON × ION-AVE - 2RDS-ON × IOFF-AVE - ESR × ION−AVE - ESR × IOFF-AVE )
= C1 × (2VIN
− VOUT
−
2R DS −ON
×
IOUT
D
−
2R DS−ON
×
IOUT
1− D
-
ESR
×
IOUT
D
-
ESR
×
IOUT
1- D
)
=
C1
× [2VIN
−
VOUT
− (2RDS−ON
+ ESR) × IOUT
×
1
D(1 −
D) ]
………(13)
Thus the output current can be written as
IOUT = f × ∆Q = f × (QON − QOFF )
=
f
× C1
× [2VIN
−
VOUT
-
(2R DS-ON
+
ESR) × IOUT
×
1
D(1 -
D)
]
(14)
When the duty cycle is 0.5, the output current can be written as:
IOUT
=
f × C1 × [2VIN
− VOUT
− (2RDS−ON
+ ESR) × IOUT
×
1
0.5(1 −
0.5)
]
= fC1 × [2VIN − VOUT − (8RDS−ON + 4ESR) × IOUT ]
And equation (15) can be re-written as:
2VIN
− VOUT
=
1
fC1
× IOUT
+ (8RDS−ON
+ 4ESR) × IOUT
(15)
(16)
According the equation (16), when the duty cycle
is 0.5, the equivalent circuit of charge pump is
shown in Fig. 22. The term 8RDS-ON is the total
effect of switching resistance, 1/fC1 is the effect
of flying capacitor and 4ESR is its equivalent
resistance.
From the equivalent circuit shown in Fig. 22, it is
seen that the terms 1/fC1, 4ESR and 8RDS-ON
should be as small as possible to get large output
current. However, for users, since the RDS-ON is
fixed and manufactured in IC, what we can do is
to lower 1/fC1 and ESR. However even the effect
of 1/fC1 and ESR can be kept as small as
possible, the term 8RDS-ON still dominates the
role that limits the maximum output current.
2VIN
IOUT
VOUT
1/fC1 8RDS-ON 4ESR
COUT
LOAD
Fig. 22 The euqivalent circuit of charge pump
Layout Considerations
Due to the switching frequency and high transient
current of AIC1845, careful consideration of PCB
layout is necessary. To achieve the best
performance of AIC1845, minimize the distance
between every two components and also
minimize every connection length with a
maximum trace width. Make sure each device
connects to immediate ground plane. Fig. 23 to
Fig. 25 show the recommended layout.
11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet AIC1845.PDF ] | |
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