SC2308A
POWER MANAGEMENT
Features
600kHz Step-Up Switching
Regulator with 2.2A, 45V Switch
Description
The SC2308A is a 600kHz current-mode switching regulator
with an integrated low-side 2.2A power transistor. The oper-
ating supply voltage of the SC2308A ranges from that of a
single Li-ion cell to various PC board power supplies. The
internal switch is rated at 45V, making the device suitable
for high voltage boost and SEPIC applications. The SC2308A
shuts down to less than µA of supply current.
The SC2308A uses peak current-mode PWM control for ease
of loop compensation and excellent transient response.
Cycle-by-cycle current limiting lowers power transistor
dissipation. An internal soft-start timer prevents output
overshoot and limits the input current during start-up.
Thermal shutdown prevents the chip from overheating.
Input Voltage Range: 2.6V to 20V
Boost and SEPIC Topologies
Up to 40V Output in Boost Topology
Integrated 2.2A/45V Switch
600kHz Constant Switching Frequency
Current-Mode Control Eases Compensation
Cycle-by-Cycle Current-Limiting
Internal Soft-Start
Thermal Shutdown Protection
Low Shutdown Current (<µA)
8-Pin SO Lead-Free Package
Fully WEEE and RoHS Compliant
Applications
Telecommunication Equipment
Point of Load DC-DC Converters
Portable Devices
Typical Application Circuit
V
IN
5V
L
10µH
D
1
SS22
SW
SC2308A
FB
COMP
C
4
470pF
R
3
200k
GND
R
2
11.3k
R
1
100k
C
3
22µF
C
2
22µF
V
OUT
12V, 0.8A
E fficiency vs Load C urrent
V
OUT
= 12V
100
90
80
E fficiency (%)
70
60
50
40
30
V
IN
= 5V
IN
OFF ON
C
1
4.7µF
EN
L: Coilcraft DO3316P103
D
1
: ON SS22
C
1
: Murata GRM31CR61A475K
C
2
,C
3
: Murata GRM31CR61C226K
20
0
200
400
600
800
Load Current (mA)
Figure 1. 5V to 12V Step-Up Converter
Rev. 2.0
SC2308A
Pin Configuration
Ordering Information
Device
SC2308ASTRT
() (2)
Top View
SC2308AEVB
Package
SO-8
Evaluation Board
COMP 1
FB 2
EN 3
GND 4
8 NC
7 NC
6 IN
5 SW
Notes:
() Available in tape and reel only. A reel contains 2,500 devices.
(2) Available in lead-free package only. Device is WEEE and RoHS
compliant and halogen free.
θ
JA
= 160°C/W
8-Lead SOIC
Marking Information
Top View
SC2308A
yyww
xxxxx
yyww - Date Code
xxxxx - Semtech Lot Number
2
SC2308A
Absolute Maximum Ratings
IN to GND………………………………………… -0.3V to 24V
SW …………………………………………………-0.3V to 45V
EN ……………………………………………-0.3V to V
IN
+ 0.3V
FB …………………………………………… -0.3V to V
IN
+ 0.3V
COMP ……………………………………… -0.3V to V
IN
+ 0.3V
ESD Protection Level
()
…………………………………
3.5kV
Recommended Operating Conditions
Junction Temperature Range………………… -40°C to +05°C
V
IN
………………………………………………… 2.6V to 20V
Thermal Information
Θ
JA
, 8-Lead SOIC
(2)
…………………………………… 60°C/W
Maximum Junction Temperature …………………… +50 °C
Storage Temperature Range ……………… -65°C to +50°C
Peak IR Reflow Temperature (0s to 30s) …………… +260°C
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:
() Tested according to JEDEC standard JESD22-A4-B.
(2) Calculated from package in still air, mounted to 3” x 4.5”, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD5 standards.
Electrical Characteristics
Unless otherwise noted: V
IN
= V
EN
= 3V, T
J
= -40°C to 05°C. Typical values are at T
J
= 25°C.
Parameter
Input Supply
Maximum Operating V
IN
V
IN
Start Voltage
Shutdown Supply Current
Quiescent Supply Current
Control Loop
Feedback Regulation Voltage
V
REF
Line Regulation
FB Pin Input Bias Current
Error Amplifier Transconductance
Error Amplifier Open-Loop Gain
COMP to Switch Current Gain
Soft-Start
Soft-Start Time
(3)
Symbol
Conditions
Min
Typ
Max
Units
V
IN(MAX)
V
IN
Rising
V
EN
= 0
I
Q
V
FB
= .5V (Not Switching)
2.45
0.0
.3
20
2.6
.8
V
V
µA
mA
V
REF
V
IN
= 3V to 20V
I
FB
g
m
A
V
FB in Regulation
V
COMP
= .V,
DI
COMP
= ± 0.5µA
.20
.22
0.002
-5
47
5
4
.24
0.005
-25
V
%/V
nA
µW
-
dB
A/V
t
SS
3
ms
Notes:
(3) Time taken for the error amplifier soft-start input to rise from 0 to .22V.
3
SC2308A
Electrical Characteristics (continued)
Parameter
Oscillator
Switching Frequency
Minimum Switch Off-Time
Minimum Switch On-Time
Minimum Duty Cycle
Maximum Duty Cycle
Power Switch
Switch Current Limit
(4)
Switch Saturation Voltage
Switch Leakage Current
Enable Pin
High Voltage Threshold
Low Voltage Threshold
V
IH
V
IL
V
EN
=0V
Enable Pin Current
I
EN
V
EN
=2V
V
EN
=6V
Over Temperature Protection
Thermal Shutdown Temperature
Hysteresis
T
SHDN
T
HYST
T
j
rising
60
2
O
Unless otherwise noted: V
IN
= V
EN
= 3V, T
J
= -40°C to 05°C. Typical values are at T
J
= 25°C.
Symbol
Conditions
Min
Typ
Max
Units
f
SW
t
OFF(MIN)
t
ON(MIN)
D
MIN
D
MAX
500
630
60
200
750
kHz
ns
ns
0
87
96
%
%
I
LIM
V
CESAT
I
LK
I
SW
=2.2A
V
SW
=2V
2.2
2.9
320
0.
3.7
480
0.5
A
mV
µA
2
0.3
0.0
3.3
3
0.
5.
25
V
V
µA
C
C
O
Notes:
(4) Switch current limit does not vary with duty cycle.
4
SC2308A
Typical Characteristics
Efficiency vs Load Current
V
OUT
= 5V
100
90
80
V
IN
= 3.3V
100
90
80
E fficiency (%)
V
IN
= 5V
E fficiency vs Load C urrent
V
OUT
= 12V
1.23
Feedback Voltage vs Temperature
V
IN
= 3V
Efficiency (%)
60
50
40
30
20
0
200
400
600
800
1000
1200
Load Current (mA)
60
50
40
30
20
0
200
400
600
800
Load Current (mA)
Voltage (V)
70
70
V
IN
= 3.3V
1.22
1.21
1.20
-50
-25
0
25
50
o
75
100
125
Temperature ( C)
Percentage Frequency
Variation vs Temperature
5
V
IN
= 3V
Percenatge Variation (%)
500
Switc h Saturation
Voltage vs Switc h Curre nt
V
IN
= 3V
400
25
o
C
Switch Current Limit vs Temperature
3.0
105
o
C
0
S aturation Voltage (mV)
2.8
Current (A)
300
-45
o
C
2.6
-5
200
2.4
V
IN
= 3V
-10
100
2.2
-15
-50
-25
0
25
50
o
0
2.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
75
100
125
-50
-25
0
25
50
o
75
100
125
Temperature ( C)
S witch Current (A)
Temperature ( C)
IN Pin Curre nt v s Switc h Curre nt
80
V
IN
= 3V
60
Error Amplifier Open-Loop
Gain vs Temperature
55
V
IN
= 3V
Error Amplifier
Transconductance vs Temperature
50
V
IN
= 3V
45
)
Transconductance (
IN P in Current (mA)
50
40
Gain (dB)
-1
40
35
30
25
45
20
25 C
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
S witch Current (A)
o
40
-50
-25
0
25
50
o
20
75
100
125
-50
-25
0
25
50
o
75
100
125
Temperature ( C)
Temperature ( C)
5
Analog electronics
京公网安备 11010802033920号
EEWORLD
