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PDF SC631 Data sheet ( Hoja de datos )
| Número de pieza | SC631 | |
| Descripción | Fixed 4.4V Output Charge Pump Regulator | |
| Fabricantes | Semtech | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de SC631 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
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SC631
Fixed 4.4V Output
Charge Pump Regulator
POWER MANAGEMENT
Features
Description
Input voltage range — 2.9V to 5.5V
V tolerance — 4.4V ±3%
OUT
Continuous output current — 250mA
Peak output current — 500mA
Three charge pump modes: 1x, 1.5x and 2x
Output ripple ≤ 30mV for I ≤ 400mA
PP OUT
Short circuit, over-voltage, and over-temperature
protection
Soft-start functionality
Shutdown current — 0.1μA, typical
Ultra thin package — 2 x 2 x 0.6 (mm)
Fully WEEE and RoHS compliant
Applications
Mobile phones
Multi-LED backlit LCDs
PMPs
Digital video cameras
Digital still cameras
PDAs
LED camera flash
Audio amplifier power
The SC631 is a high-current voltage regulator using
Semtech’s proprietary low-noise charge pump technol-
ogy. Performance is optimized for use in single Li-Ion
battery cell applications. The regulator provides the per-
formance of a linear, low drop-out (LDO) voltage regulator
when the input is greater than 4.4V. Unlike an LDO, drop-
out is avoided when the input is less than 4.4V. Instead, a
charge pump is activated to provide voltage boost and
the head-room needed for voltage regulation.
Only two 2.2μF bucket capacitors are required to deliver
the full output current. The charge pump provides a low
EMI solution compared to inductive boost regulators.
The SC631’s charge pump has three modes of operation:
2x, 1.5x, and 1x modes. The 2x and 1.5x modes deliver
current to the load in each of two phases. The 1x mode
turns off the charge pump, delivering current through an
LDO. When active, the charge pump provides low-ripple
operationhttp://www.DataSheet4U.net/ at 200kHz, which is typically less than 30mVpp
at the output. The SC631 is capable of delivering 250mA
continuous current, with peak current to 500mA. A 22μF
output capacitor is used for decoupling the load and for
smoothing mode transitions. Hysteresis is provided to
prevent chatter between charge pump modes.
The micro lead-frame package is both small and thermally
efficient, measuring 2 x 2 x 0.6 (mm).
Typical Application Circuit
VBAT
CIN
22μF
IN
OUT
VOUT = 4.4V @ 250mA
COUT
22μF
SC631
Chip
enable
EN
GND
C1+
C1-
C2+
C2-
C1
2.2μF
C2
2.2μF
July 24, 2008
© 2008 Semtech Corporation
Patents Pending
1
datasheet pdf - http://www.DataSheet4U.net/
1 page  
SC631
Typical Characteristics
Load Regulation
25 VOUT = 4.4V, VIN = 4.2V
20
TA=85°C
15
TA=25°C
10
TA=-40°C
5
0
0 90 180 270 360 450
Output Current (mA)
PSRR versus Frequency — 1.5x Mode
0 VIN = 3.6V, VOUT = 4.4V, IOUT = 50mA
-10
-20
CIN=COUT=22μF (0805)
C =C =2.2μF (0603)
12
-30
-40
-50
-60
-70
-80
-90
-100
10
100 1000
Frequency [Hz]
10000
Line Regulation
25 VOUT = 4.4V, IOUT = 1mA
20
85°C
15
25°C
10
3.6V, 0mV
5
-40°C
0
-5
-10
-15
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
PSRR versus Frequency — 2x Mode
http://www.DataSheet4U.net/
0 VIN = 2.9V, VOUT = 4.4V, IOUT = 50mA
-10
-20
CIN=COUT=22μF (0805)
C =C =2.2μF (0603)
12
-30
-40
-50
-60
-70
-80
-90
-100
10
100 1000
Frequency [Hz]
10000
5
datasheet pdf - http://www.DataSheet4U.net/
5 Page 
SC631
Applications Information (continued)
Over-Current Protection
Over-current protection is provided to limit the output
current. When VOUT is greater than 2V, OCP limits the output
to 1A typical. The 2V threshold allows the device to
recover from excessive voltage droop during an over-
current event.
Short-Circuit Current Protection
Short-circuit current protection is provided to limit the
current that can be sourced when the output is shorted to
ground. When a short circuit forces V to drop below 2V,
OUT
the SCCP detects the condition and limits the output
current to 600mA (typical).
Over-Temperature Protection
The over-temperature circuit helps prevent the device
from overheating and experiencing a catastrophic failure.
When the junction temperature exceeds 165°C, the device
is disabled. It remains disabled until the junction tempera-
ture drops below this threshold. Hysteresis is included
that prevents the device from re-enabling until the junc-
tion temperature is reduced by 20°C.
Capacitor Selection
The SC631 is designed to use low-ESR ceramic capacitors
for the input and output bypass capacitors as well as the
charge pump bucket capacitors. Ideal performance is
achieved when the bucket capacitors are exactly equal.
The value of input and output decoupling capacitors will
vary with system requirements. For best ripple perfor-
mance C and C are normally 22μF and the bucket
IN OUT
capacitors C and C are 2.2μF. For low profile designs, two
12
10μF capacitors may be used in place of each 22μF.
When selecting capacitors for the application, the DC
voltage characteristic of the capacitor should be consid-
ered. The value of capacitance at the DC operating voltage
may be considerably lower than the rated value. The fol-
lowing table lists recommended capacitor values which
have been chosen to minimize the impact of this
limitation.
Table 1 — Recommended Capacitors
Capacitor
Value
μF
Case
Size
Notes
C ,C
IN OUT
C
BUCKET
C
BUCKET
Typical output V ≤ 20mV in all
PP
charge pump modes
22 0805
Typical input ripple ≤ 100mV in all
charge pump modes
Required for the full rated output
2.2 0603 current
Useful for load current up to
2.2 0402
300mA
NOTE: Use only X5R type capacitors, with a 6.3V rating or higher
http://www.DataSheet4U.net/
The highest capacitance values in the smallest package
sizes tend to have poor DC voltage characteristics. The
highest value 0402 size capacitor retains as little as 35% of
its rated value at 5VDC. The same value chosen in the next
larger package size (0603) retains about 60% of its rated
value at 5VDC.
11
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11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet SC631.PDF ] | |
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