SC631 Datasheet

SC631
Fixed 4.4V Output
Charge Pump Regulator
POWER MANAGEMENT
Features
Description
„
The SC631 is a high-current voltage regulator using
Semtech’s proprietary low-noise charge pump technology. Performance is optimized for use in single Li-Ion
battery cell applications. The regulator provides the performance of a linear, low drop-out (LDO) voltage regulator
when the input is greater than 4.4V. Unlike an LDO, dropout 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.
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Input voltage range — 2.9V to 5.5V
VOUT tolerance — 4.4V ±3%
Continuous output current — 250mA
Peak output current — 500mA
Three charge pump modes: 1x, 1.5x and 2x
Output ripple ≤ 30mVPP for IOUT ≤ 400mA
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
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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
operation 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.
Mobile phones
Multi-LED backlit LCDs
PMPs
Digital video cameras
Digital still cameras
PDAs
LED camera flash
Audio amplifier power
The micro lead-frame package is both small and thermally
efficient, measuring 2 x 2 x 0.6 (mm).
Typical Application Circuit
CIN
22μF
VBAT
IN
OUT
VOUT = 4.4V @ 250mA
COUT
22μF
SC631
Chip
enable
EN
C1+
C1C2+
GND
C2-
C1
2.2μF
C2
2.2μF
Patents Pending
July 24, 2008
© 2008 Semtech Corporation
1
SC631
Pin Configuration
GND
Ordering Information
1
8
C2-
TOP VIEW
C1+
2
7
C2+
C1-
3
6
OUT
IN
4
5
EN
Device
Package
SC631ULTRT(1)(2)
MLPD-UT-8 2x2
SC631EVB
Evaluation Board
Notes:
(1) Available in tape and reel only. A reel contains 3,000 devices.
(2) Lead-free package only. Device is WEEE and RoHS compliant.
T
MLPD-UT-8; 2x2, 8 LEAD
θJA = 68°C/W
Marking Information
631
yw
yw = Datecode
2
SC631
Absolute Maximum Ratings
Recommended Operating Conditions
IN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0
Ambient Temperature Range (°C) . . . . . . . . -40 ≤ TA ≤ +85
OUT (V). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to +6.0
IN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 ≤ VIN ≤ 5.5
C1+, C2+ (V) . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to (VOUT + 0.3)
Pin Voltage — All Other Pins (V) . . . . . . . . . -0.3 to (VIN + 0.3)
OUT pin — Short Circuit Duration . . . . . . . . . . Continuous
ESD Protection Level(2) (kV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Thermal Information
Thermal Resistance, Junction to Ambient(1) (°C/W) . . . . 68
Maximum Junction Temperature (°C) . . . . . . . . . . . . . . +150
Storage Temperature Range (°C) . . . . . . . . . . . . -65 to +150
Peak IR Reflow Temperature (10s to 30s) (°C) . . . . . . . +260
Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters
specified in the Electrical Characteristics section is not recommended.
NOTES
(1) Calculated from package in still air, mounted to 3 x 4.5 (in), 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards.
(2) Tested according to JEDEC standard JESD22-A114-B.
Electrical Characteristics
Unless otherwise specified: TA = +25°C for Typ, -40°C to +85°C for Min and Max; C1 = C2 = 2.2μF (ESR < 0.03Ω); CIN = COUT = 22μF; VIN = 2.9V to 5.5V
Parameter
Symbol
Condition
Min
Typ
Max
Units
Output Voltage
VOUT
VIN = 4.2V, IOUT = 1mA
4.27
4.4
4.53
V
Output Voltage Ripple
VPP
IOUT ≤ 400mA
Maximum Output Current
IOUT
30
mV
Peak Load - thermally limited(1),
TJ <150°C, 3.33V ≤ VIN ≤ 5.5V
500
mA
Continuous Load, TA ≤ 55°C, 2.92V ≤ VIN ≤ 4.2V
325
mA
Continuous Load
250
mA
Shutdown Current
ISD
Shutdown (EN = GND), VIN = 3.6V
0.1
2
μA
Total Quiescent Current
IQ
EN high, IOUT = 1mA
1.5
2.5
mA
Charge Pump Frequency
fPUMP
VIN = 3.2V
200
kHz
tSU
(EN transitions from low to high),
4.27V ≤ VOUT ≤ 4.53V, No load
400
μs
Line Regulation
ΔVLINE
IOUT = 1mA, 2.85V ≤ VIN ≤ 4.2V
21
mV
Load Regulation
ΔVLOAD
VIN =4.2V, 1mA ≤ IOUT ≤ 400mA
33
mV
Start-Up Time
3
SC631
Electrical Characteristics (continued)
Parameter
Symbol
Condition
Min
EN Input High Threshold
VIH
VIN = 5.5V
1.6
EN Input Low Threshold
VIL
VIN = 2.7V
0.4
V
EN Input High Current
IIH
VIN = 5.5V
2
μA
EN Input Low Current
IIL
VIN = 5.5V
2
μA
Open-Loop Output Resistance
Typ
Max
Units
V
1x mode
0.25
Ω
1.5x mode, VIN = 3.7V
2.85
Ω
2x mode, VIN = 3.1V
2.9
Ω
V TRANS 1X
IOUT = 200mA
4.41
V
V TRANS 1.5X
IOUT = 200mA
3.31
V
ISC
VOUT = 0V, IOUT = IIN
300
600
980
mA
VOUT > 2V, 1x mode
0.6
1.2
2.0
A
VOUT > 2V, 1.5x and 2x modes
1.2
2.0
2.8
A
ROUT
Mode Transition Voltage (2)
Fault Protection
Short-Circuit Current
Input Current Limit
ILIMIT
VOUT ≤ 2V, IOUT = IIN
700
mA
TOTP
Rising Threshold
165
°C
THYS
Hysteresis(3)
20
°C
Over Temperature
Notes:
(1) Thermal limitation is dependent upon the thermal performance of the printed circuit board in support of the package standard of 68° C/W.
(2) Voltage at the IN pin where a mode transition takes place in the charge pump with VIN falling.
(3) Guaranteed by design - not tested in production.
4
SC631
Typical Characteristics
Line Regulation
Load Regulation
TA=25°C
20
TA=85°C
15
10
TA=-40°C
5
0
0
90
VOUT = 4.4V, IOUT = 1mA
25
Output Voltage Variation — ΔV LINE (mV)
Output Voltage Variation — ΔVLOAD (mV)
25
VOUT = 4.4V, VIN = 4.2V
180
270
Output Current (mA)
360
20
85°C
15
25°C
10
3.6V, 0mV
0
-5
-10
-15
450
2.7
PSRR versus Frequency — 1.5x Mode
0
-20
-20
-30
-30
-40
-40
-50
-60
4.7
5.1
5.5
VIN = 2.9V, VOUT = 4.4V, IOUT = 50mA
-70
-80
-90
-90
-100
10
-100
10
10000
CIN=COUT=22μF (0805)
C1=C2=2.2μF (0603)
-60
-80
1000
3.9
4.3
Input Voltage (V)
-50
-70
Frequency [Hz]
3.5
-10
C1=C2=2.2μF (0603)
Gain [dB]
Gain [dB]
0
CIN=COUT=22μF (0805)
100
3.1
PSRR versus Frequency — 2x Mode
VIN = 3.6V, VOUT = 4.4V, IOUT = 50mA
-10
-40°C
5
1000
100
10000
Frequency [Hz]
5
SC631
Typical Characteristics (continued)
Efficiency — 10mA
100
Efficiency — 50mA
VOUT = 4.4V, IOUT = 10mA
100
VOUT = 4.4V, IOUT = 50mA
1.5x Mode
1.5x Mode
90
Efficiency(%)
Efficiency(%)
90
80
70
Mode
Transition
Hysteresis
60
50
4.2
3.9
3.6
80
Mode
Transition
Hysteresis
70
2x Mode
2x Mode
3.3
3.0
60
50
4.2
2.7
3.9
3.6
VIN (V)
Efficiency — 100mA
100
3.3
3.0
2.7
3.0
2.7
Efficiency — 200mA
VOUT = 4.4V, IOUT = 100mA
100
1.5x Mode
90
VIN (V)
VOUT = 4.4V, IOUT = 200mA
90
Efficiency(%)
Efficiency(%)
1.5x Mode
80
70
Mode
Transition
Hysteresis
80
70
2x Mode
60
60
Mode
Transition
Hysteresis
2x Mode
50
4.2
50
3.6
3.9
3.3
3.0
2.7
4.2
3.9
3.6
Efficiency — 300mA
100
Efficiency — 400mA
VOUT = 4.4V, IOUT = 300mA
100
VOUT = 4.4V, IOUT = 400mA
90
90
1.5x Mode
Efficiency(%)
Efficiency(%)
1.5x Mode
80
Mode
Transition
Hysteresis
70
80
70
60
60
2x Mode
50
4.2
3.3
VIN (V)
VIN (V)
2x Mode
50
3.9
3.6
3.3
VIN (V)
3.0
2.7
4.2
3.9
3.6
VIN (V)
3.3
3.0
2.7
6
SC631
Typical Characteristics (continued)
Ripple — 1.5x Mode
Ripple — 1x Mode
VIN = 4.2V, VOUT= 4.4V, IOUT = 400mA
VIN = 5.2V, VOUT = 4.4V, IOUT = 400mA
VIN -PP (100mV/div)
VIN -PP (20mV/div)
VOUT -PP (20mV/div)
IOUT (200mA/div)
VOUT -PP (100mV/div)
400mA
400mA
IOUT (200mA/div)
CIN=COUT=22μF (0805)
CIN=COUT=22μF (0805)
C1=C2=2.2μF (0603)
0mA
0mA
C1=C2=2.2μF (0603)
Time (10μs/div)
Time (10μs/div)
Startup (No Load)
Ripple — 2x Mode
VIN = 3.2V, VOUT = 4.4V, IOUT = 400mA
VIN = 3.6V, IOUT = 0mA
VIN -PP (50mV/div)
VEN (2V/div)–
0V—
VOUT -PP (50mV/div)
IOUT (200mA/div)
400mA
VOUT (2V/div)–
CIN=COUT=22μF (0805)
0V—
CIN=COUT=22μF (0805)
0V—
C1=C2=2.2μF (0603)
0mA
C1=C2=2.2μF (0603)
IOUT (200mA/div)
Time (200μs/div)
Time (10μs/div)
Quiescent Current
Startup (400mA)
VOUT = 5V, IOUT = 1mA
VIN = 3.6V, IOUT = 400mA
2.5
85C
25C
2.0
VEN (2V/div)–
IQ (mA)
0V —
1.5
-45C
VOUT (2V/div)–
0V—
0V—
IOUT (200mA/div)–
1.0
CIN=COUT=22μF (0805)
C1=C2=2.2μF (0603)
Time (200μs/div)
0.5
4.20
3.94
3.68
3.42
3.16
2.90
VIN (V)
7
SC631
Pin Descriptions
Pin
Pin Name
Pin Function
1
GND
Ground — connect to ground plane with multiple vias
2
C1+
Positive terminal of bucket capacitor 1
3
C1-
Negative terminal of bucket capacitor 1
4
IN
Input supply voltage
5
EN
Chip enable — active-high
6
OUT
Output
7
C2+
Positive terminal of bucket capacitor 2
8
C2-
Negative terminal of bucket capacitor 2
T
Thermal Pad
This pad is for heat sinking and is not connected internally. It must be connected to a ground plane using
multiple vias.
8
SC631
Block Diagram
IN 4
LDO
2 C1+
200kHz
3 C17 C2+
EN 5
Logic
Control
Reference
Voltage
Generator
CHARGE
PUMP
8 C26 OUT
1 GND
9
SC631
Applications Information
The SC631 is a 4.4V output charge pump regulator
designed to support up to 325mA (TA ≤ 55°C, 2.92V ≤ VIN ≤
5.5V) and 250mA (TA ≤ 85°C, 2.90V ≤ VIN ≤ 5.5V) of continuous current. SC631 applications include power for LEDs
and audio amplifiers in portable handheld equipment.
SC631 may be used in conjunction with regulated current
sink devices such as the SC620 Octal LED Driver or with
ballast resistors.
The SC631 has three operating modes — 1x, 1.5x, and 2x.
The 1x mode is a linear series regulation mode with a low
open-loop output resistance of only 250mΩ. The 1x mode
functions as a low-noise linear regulator. The 1.5x and 2x
modes are a low noise, constant frequency, constant duty
cycle switch mode, using two bucket capacitors. One
bucket supports the full output current while the other
bucket charges from the input. The two buckets exchange
roles in the next phase, supplying continuous output
current in both phases and reducing the need for a large
output decoupling capacitor. The constant frequency,
constant duty cycle operation also produces predictable
constant frequency harmonics.
Mode Transition Hysteresis
Hysteresis is provided to prevent chatter between charge
pump modes for input steps of up to 120mV. For optimum
transient performance, it is recommended for the supply
decoupling capacitance be large enough to prevent steps
greater than 120mV. Normally CIN = 22uF is sufficient to
minimize supply transients during the charge pump mode
transitions.
Thermal Resistance
The SC631 package is thermally efficient when the circuit
board layout connects the thermal pad through multiple
vias to the ground plane. The thermal resistance rating is
dependent upon the connection between the thermal
pad and the ground plane. A layout that is done correctly
should keep the junction temperature below the over-
temperature limit while operating the SC631 within the
specified electrical conditions. A poor layout may allow
the junction temperature to reach the over temperature
limit, so it is important to maintain adequate ground
plane around the device to maximize heat transfer to the
PCB.
Temperature Derating
The VIN supply range and ambient temperature range of
the application should be compared with the following
derating curve to determine the maximum safe continuous load current. The DC operating points beneath each
curve are in the safe operating temperature range of the
MLP package.
450
400
Derating for VIN < 4.2V
350
IOUT (mA)
General Description
300
Derating for VIN < 5.5V
250
200
150
35
45
55
65
Ambient Temp (°C)
75
85
Maximum Continuous Output
Protection Circuitry
The SC631 also provides protection circuitry that prevents the device from operating in an unspecified state.
These functions include:
•
•
•
Over-Current Protection (OCP)
Short-Circuit Current Protection (SCCP)
Over-Temperature Protection (OTP)
10
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 overcurrent 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 VOUT to drop below 2V,
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 temperature drops below this threshold. Hysteresis is included
that prevents the device from re-enabling until the junction 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 performance CIN and COUT are normally 22μF and the bucket
capacitors C1 and C2 are 2.2μF. For low profile designs, two
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 considered. The value of capacitance at the DC operating voltage
may be considerably lower than the rated value. The following 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
Typical output VPP ≤ 20mV in all
charge pump modes
CIN , COUT
22
0805
CBUCKET
2.2
0603
Required for the full rated output
current
CBUCKET
2.2
0402
Useful for load current up to
300mA
Typical input ripple ≤ 100mV in all
charge pump modes
NOTE: Use only X5R type capacitors, with a 6.3V rating or higher
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
SC631
Applications Information (continued)
PCB Layout Considerations
Poor layout can degrade the performance of the regulator and can be a contributory factor in EMI problems,
ground bounce, thermal issues, and resistive voltage
losses. Poor regulation and instability can result.
The following design rules are recommended:
1. Place the bucket capacitors as close to the device as
possible and on the same side of the board. Use short
wide copper areas between the capacitor pins and
the device pins.
2. Place the input and output decoupling capacitors
as close as possible to the device and connect these
capacitors’ ground pads together to the ground plane
using multiple vias through a short wide copper
area.
3. Connect pin 1 directly to the copper area under the
thermal pad.
4. The thermal pad at the center of the device is not
electrically connected. Connect this pad to the
ground plane using multiple vias.
5. Use a ground plane to further reduce noise
interference on sensitive circuit nodes.
SC631
C2-
C1
C1+
GND
GND
C2
C2+
C1-
VOUT
VIN
EN
COUT
CIN
EN
12
SC631
Outline Drawing — MLPD-UT-8 2x2
B
D
A
DIMENSIONS
DIM
E
PIN 1
INDICATOR
(LASER MARK)
A
SEATING
PLANE
aaa C
A2
A1
C
A
A1
A2
b
D
D1
E
E1
e
L
N
aaa
bbb
MILLIMETERS
INCHES
MIN
.020
.000
NOM
-
MAX
.024
.002
(.006)
.010 .012
.079 .083
.067 .071
.079 .083
.031 .035
.020 BSC
.014 .016
.012
8
.003
.004
.007
.075
.061
.075
.026
MIN
0.50
0.00
NOM
-
(0.1524)
0.18 0.25
1.90 2.00
1.55 1.70
1.90 2.00
0.65 0.80
0.50 BSC
0.30 0.35
8
0.08
0.10
MAX
0.60
0.05
0.30
2.10
1.80
2.10
0.90
0.40
D1
1
2
LxN
E/2
E1
N
bxN
bbb
e
C A B
e/2
D/2
NOTES:
1.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2.
COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS.
13
SC631
Land Pattern — MLPD-UT-8 2x2
H
DIMENSIONS
R
(C)
K
G
Z
Y
P
DIM
INCHES
MILLIMETERS
C
(.077)
(1.95)
G
.047
1.20
H
.067
1.70
K
.031
0.80
P
.020
0.50
R
.006
0.15
X
.012
0.30
Y
.030
0.75
Z
.106
2.70
X
NOTES:
1.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
3.
THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD
SHALL BE CONNECTED TO A SYSTEM GROUND PLANE.
FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR
FUNCTIONAL PERFORMANCE OF THE DEVICE.
Contact Information
Semtech Corporation
Power Management Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805) 498-2111 Fax: (805) 498-3804
www.semtech.com
14