|
|
PDF LTC3203B-1 Data sheet ( Hoja de datos )
| Número de pieza | LTC3203B-1 | |
| Descripción | 500mA Output Current Low Noise Dual Mode Step-Up Charge Pumps | |
| Fabricantes | Linear | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LTC3203B-1 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
FEATURES
■ Selectable Dual Mode Operation: 1:1.5 or 1:2
■ High Output Current: Up to 500mA
■ Low Noise Constant Frequency (1MHz/0.9MHz)
Operation*
■ VIN Range: 2.7V to 5.5V
■ Adjustable Output Voltage (LTC3203/LTC3203B)
■ User Selectable Fixed Output Voltages: 4.5V or 5V
(LTC3203-1 and LTC3203B-1)
■ Burst Mode® Operation with
IQ ~ 120µA (LTC3203/LTC3203-1)
■ Constant Freqency Operation at All Loads
(LTC3203B/LTC3203B-1)
■ Soft-Start Limits Inrush Current at Turn-On
■ Short-Circuit/Thermal Protection
■ Shutdown Disconnects Load from Input
■ Shutdown Current: < 1µA
■ Available in a 10-pin (3mm × 3mm) DFN Package
U
APPLICATIO S
■ High Current LED Backlight Supply for
Cellphones/PDAs
■ Cellphone Camera Light Supply
■ General Purpose 3.3V or Li-Ion to 5V Supply
■ USB ON THE GO(OTG) Devices
LTC3203/LTC3203-1
LTC3203B/LTC3203B-1
500mA Output Current
Low Noise Dual Mode
Step-Up Charge Pumps
DESCRIPTIO
The LTC®3203/LTC3203-1/LTC3203B/LTC3203B-1 are low
noise, high efficiency charge pump DC/DC converters
capable of driving loads up to 500mA from a 2.7V to 5.5V
input. Low external parts count (two flying capacitors and
bypass capacitors at VIN and VOUT) make the LTC3203
family ideally suited for small, battery-powered applica-
tions.
Built-in soft-start circuitry prevents excessive inrush
current during start-up. High switching frequency enables
the use of small external capacitors. The LTC3203/
LTC3203-1 feature Burst Mode operation at light load to
achieve high efficiency whereas the LTC3203B/
LTC3203B-1 operate at constant frequency to achieve
lowest noise operation.
The LTC3203-1/LTC3203B-1 have a user selectable fixed
output voltage of 4.5V or 5V to power LEDs or logic
circuits. The FB pin of the LTC3203/LTC3203B can be used
to program the desired output voltage. The parts are short-
circuit and overtemperature protected and are available in
a low profile (3mm × 3mm) DFN package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
*Protected by U.S. Patents including 6411531.
TYPICAL APPLICATIO
VIN
2.2µF
ON/OFF
R1*
100k
2.2µF
SHDN VSEL
LTC3203-1
VIN VOUT
C1+ C2+
C1– C2–
MODE GND
IOUT(MAX)
300mA
300mA
500mA
500mA
VSEL
LOW
HIGH
LOW
HIGH
VOUT
4.5V
5V
4.5V
5V
*R1
316k
357k
357k
402k
OUTPUT PROGRAMMING
2.2µF
VOUT
500mA
10µF
3203 F02
Efficiency vs VIN at 300mA Load Current
100
90
80
VOUT = 5V
70
VOUT = 4.5V
60
50
40
30
20
10
0
2.5 3 3.5 4 4.5 5 5.5
VIN (V)
3203 G05
32031fa
1
1 page  
LTC3203/LTC3203-1
LTC3203B/LTC3203B-1
TYPICAL PERFOR A CE CHARACTERISTICS
No-Load Input Current vs Supply
Voltage (LTC3203/LTC3203-1)
160
140 2x MODE
120
1.5x MODE
100
80
60
40
20
0
2.5 3 3.5 4 4.5 5 5.5
VIN (V)
3203 G10
Input and Output Ripple
(1.5x Mode)
Burst Mode Current Threshold
vs Supply Voltage
(LTC3203/LTC3203-1)
500
450
400
350
300
250
200
150 1.5x MODE
100
50 2x MODE
0
2.5 3 3.5 4 4.5 5 5.5
VIN (V)
3203 G11
Input and Output Ripple
(2x Mode)
Extra Input Current vs Load
Current (LTC3203/LTC3203-1)
100
10
2x MODE
IIN – 2 • ILOAD
1
1.5x MODE
IIN – 1.5 • ILOAD
0.1
0.01
0.01
0.1
1 10
ILOAD (mA)
100 1000
3209 G12
Load Transient (1.5x Mode)
VIN
20mV/DIV
AC-COUPLED
VOUT
20mV/DIV
AC-COUPLED
VIN
20mV/DIV
AC-COUPLED
VOUT
20mV/DIV
AC-COUPLED
VOUT
100mV/DIV
AC-COUPLED
500mA
IOUT 100mA
VIN = 4V
CIN = 2.2µF
COUT = 10µF
IOUT = 300mA
1.5x MODE
500ns/DIV
3203 G13
Load Transient (2x Mode)
VOUT
100mV/DIV
AC-COUPLED
IOUT 500mA
100mA
VIN = 3.6V
CIN = 2.2µF
COUT = 10µF
2x MODE
20µs/DIV
3203 G16
VIN = 3.6V
CIN = 2.2µF
COUT = 10µF
IOUT = 300mA
2x MODE
500ns/DIV
3203 G14
VFB Set Point vs Supply Voltage
(LTC3203/LTC3203B)
0.94
0.93
0.92
TA = –40°C
0.91
0.90
TA = 25°C
TA = 85°C
0.89
0.88
2.5 3 3.5 4 4.5
VIN (V)
5 5.5
3203 G17
VIN = 4V
CIN = 2.2µF
COUT = 10µF
1.5x MODE
20µs/DIV
3203 G15
VFB vs Load Current
(LTC3203/LTC3202B)
0.96
0.94
0.92
VIN = 4V
0.90 1.5x MODE
0.88 VIN = 3.6V
2x MODE
0.86
0.84
0.82
0 50 100 150 200 250 300 350 400 450 500
ILOAD (mA)
3203 G18
32031fa
5
5 Page 
LTC3203/LTC3203-1
LTC3203B/LTC3203B-1
APPLICATIO S I FOR ATIO
resistor RX. Thus, this configuration will have the highest
loop gain giving it the lowest closed-loop output resis-
tance. Likewise it will also require the largest amount of
output capacitance to preserve stability.
Effective Open Loop Output Resistance (ROL)
The effective open loop output resistance (ROL) of a
charge pump is a very important parameter, which deter-
mines its strength. The value of this parameter depends on
many factors such as the oscillator frequency (fOSC), the
value of the flying capacitor (CFLY), the non-overlap time,
the internal switch resistances (RS), and the ESR of the
external capacitors.
Maximum Available Output Current
Figure 3 shows how the LTC3203/LTC3203-1/LTC3203B/
LTC3203B-1 can be modeled as a Thevenin-equivalent
circuit.
Thus the maximum available output current and voltage
can be calculated from the effective open-loop output
resistance, ROL, and the effective output voltage, 1.5VIN
(in 1.5x mode) or 2VIN (in 2x mode). From Figure 3, the
available current is given by:
IOUT
= 1.5VIN − VOUT
ROL
In
1.5x
mode
IOUT
=
2VIN − VOUT
ROL
In
2x
mode
As evident from the above two equations, with the same
VIN and ROL, the 2x mode will give more output current
than the 1.5x mode.
1.5VIN
OR
2VIN
ROL
–+
+
VOUT
–
3203 F03
Figure 3. Charge Pump Open-Loop Thevenin-Equivalent Circuit
Programming the MODE Pin
By connecting a resistor divider to the MODE pin, the VIN
voltage at which the chip switches modes can be accu-
rately programmed.
When VIN ramps up, the voltage at the MODE pin crosses
VMODEH and the chip switches from 2x mode to 1.5x mode.
When VIN starts to drop, the voltage at the MODE pin
crosses VMODEL and the chip switches back to 2x mode.
The MODE pin resistor ratio must be selected such that at
the switch point the output is still able to maintain regula-
tion at maximum IOUT:
1.5 • VIN(1.5x) – VOUT > IOUT • ROL(1.5X)
The minimum VIN operating in 1.5x mode occurs at the
switch point where:
VIN
=
VMODEL
•
⎛
⎝⎜
RMODE1
RMODE2
+
⎞
1⎠⎟
therefore:
1.5
•
VMODEL
•
⎛
⎝⎜
RMODE1
RMODE2
+
⎞
1⎠⎟
> ROL(1.5X)(MAX) •IOUT(MAX) + VOUT(MIN)
RMODE1 > VOUT(MIN) + ROL(1.5x)(MAX) •IOUT(MAX) – 1
RMODE2
1.5 • VMODEL
VIN 7
LTC3203/
LTC3203B 6
MODE
9, 11
GND
RMODE1
RMODE2
CIN
3203 F04
Figure 4
32031fa
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LTC3203B-1.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LTC3203B-1 | 500mA Output Current Low Noise Dual Mode Step-Up Charge Pumps | Linear |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |