SC4502/SC4502H
1.4Amp, 2MHz Step-Up Switching
Regulator with Soft-Start
POWER MANAGEMENT
Description
The SC4502/SC4502H is a high-frequency current-mode
step-up switching regulator with an integrated 1.4A
power transistor. Its high switching frequency (program-
mable up to 2MHz) allows the use of tiny surface-mount
external passive components. Programmable soft-start
eliminates high inrush current during start-up. The inter-
nal switch is rated at 32V (40V for the SC4502H) mak-
ing the converter suitable for high voltage applications
such as Boost, SEPIC and Flyback.
The operating frequency of the SC4502/SC4502H can
be set with an external resistor. The ability to set the
operating frequency gives the SC4502/SC4502H design
flexibilities. A dedicated COMP pin allows optimization of
the loop response. The SC4502/SC4502H is available
in thermally enhanced 10-pin MLPD package.
Features
Low saturation voltage switch: 210mV
(250mV for the SC4502H)
Constant switching frequency current-mode control
Programmable switching frequency up to 2MHz
Soft-Start function
Input voltage ranges from 1.4V to 16V
Output voltage up to 32V (40V for the SC4502H)
Low shutdown current
Adjustable undervoltage lockout threshold
Small low-profile thermally enhanced lead free
package. This product is fully WEEE and RoHS
compliant.
Applications
Flat screen LCD bias supplies
TFT bias supplies
XDSL power supplies
Medical equipment
Digital video cameras
Portables devices
White LED power supplies
Typical Application Circuit
VIN
5V
8
OFF ON
C1
2.2µF
3
10
IN
SHDN
SC4502
SS
GND
C3
47nF
4,5
COMP
ROSC
9
R4
C4
6,7
SW
FB
2
1
R3
C6
R2
100K
C2
10µF
L1
D1
10BQ015
VOUT
12V
R1
866K
Efficiency
95
90
85
10.5
µ
H, 700KHz
5.3µ
H, 1.4MHz
Efficiency (%)
80
75
70
65
60
55
50
V
IN
= 5V
V
OUT
= 12V
0.0
0.1
0.2
0.3
0.4
0.5
3.3µ
H, 2MHz
All Capacitors are Ceramic.
f
(MHz)
0.7
1.4
2
R
3
(K
Ω )
R
4
(K
Ω )
33.2
59.0
73.2
23.7
9 .5 3
5.36
C
4
(pF)
1500
560
330
C
6
(pF)
-
-
22
L
1
(µH)
10.5 (Falco D08019)
5.3 (Sumida CDRH5D28)
3.3 (Coilcraf t DO1813P)
Load Current (A)
Figure 1(b). Efficiencies of 5V to 12V Boost Converters at
700KHz, 1.4MHz and 2MHz.
Figure 1(a). 5V to 12V Boost Converter.
Revision: July 25, 2005
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SC4502/SC4502H
POWER MANAGEMENT
Absolute Maximum Rating
Exceeding the specifications below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters specified
in the Electrical Characteristics section is not implied.
Parameter
Supply Voltage
SW Voltage
SW Voltage (SC4502H)
FB Voltages
SHDN Voltage
Operating Temperature Range
Thermal Resistance Junction to Ambient (MLPD-10)
Maximum Junction Temperature
Storage Temperature Range
Lead Temperature (Soldering)10 sec
Symbol
V
IN
V
SW
V
SW
V
FB
V
SHDN
T
A
θ
J A
T
J
T
STG
T
LEAD
ESD
Typ
-0.3 to 16
-0.3 to 32
-0.3 to 40
-0.3 to 2.5
-0.3 to V
IN
+ 1
-40 to +85
40
160
-65 to +150
260
2000
Units
V
V
V
V
V
°C
°C/W
°C
°C
°C
V
Electrical Characteristics
Electrical Characteristics
Parameter
Minimum Operating Voltage
Maximum Operating Voltage
Feedback Voltage
ESD Rating (Human Body Model)
Unless other specified: V
IN
= 2V, SHDN = 1.5V, R
OSC
= 7.68kΩ, -40°C < T
A
= T
J
< 85°C
Test Conditions
Min
Typ
1.3
Max
1.4
16
Unit
V
V
V
V
%
T
A
= 25°C
-40°C < T
A
< 85°C
1.5V < V
IN
< 16V
1.224
1.217
1.242
1.260
1.267
Feedback Voltage Line Regulation
FB Pin Bias Current
Error Amplifier Transconductance
Error Amplifier Open-Loop Gain
COMP Source Current
COMP Sink Current
V
IN
Quiescent Supply Current
V
IN
Supply Current in Shutdown
Switching Frequency
Maximum Duty Cycle
Minimum Duty Cycle
Switch Current Limit
Switch Saturation Voltage
Switch Saturation Voltage (SC4502H)
2005 Semtech Corp.
0.01
40
60
49
80
nA
µΩ
−1
dB
µA
µA
V
FB
= 1.1V
V
FB
= 1.4V
V
SHDN
= 1.5V, V
COMP
= 0 ( Not Switching )
V
SHDN
= 0
1.3
85
5
5
1.1
10
1.5
90
0
1.4
2
210
250
340
390
1.6
18
1.7
mA
µA
MHz
%
%
A
mV
mV
I
SW
= 1.3A
I
SW
= 1.3A
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SC4502/SC4502H
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Unless other specified: V
IN
= 2V, SHDN = 1.5V, R
OSC
= 7.68kΩ, -40°C < T
A
= T
J
< 85°C
Parameter
Swi tch Leakage C urrent
Shutdown Threshold Voltage
Shutdown Pi n C urrent
Soft-Start C hargi ng C urrent
Thermal Shutdown Temperature
Thermal Shutdown Hysteresi s
Test C onditions
V
S W
= 5V
Min
Typ
0.01
Max
1
1.18
U nit
mA
V
µA
1.02
V
SHDN
= 1.2V
V
SHDN
= 0
V
SS
= 0.3V
1.1
-4.6
0
1.5
160
10
0.1
µA
µA
°C
°C
Pin Configurations
TOP VIEW
Ordering Information
Device
(1)(2)
SC4502MLTRT
SC4502HMLTRT
S C 4502E V B
SC4502HEVB
P ackag e
MLPD-10
MLPD-10
Temp. Range( T
A
)
-40 to 85°C
-40 to 85°C
Evaluation Board
Evaluation Board
(10 Pin - MLPD, 3 x 3mm)
Notes:
(1) Only available in tape and reel packaging. A reel
contains 3000 devices for MLP package.
(2) Lead free product. This product is fully WEEE and
RoHS compliant.
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SC4502/SC4502H
POWER MANAGEMENT
Pin Descriptions
Pin
1
2
Pin Name
COMP
FB
Pin Function
The output of the internal transconductance error amplifier. This pin is used for loop compensation.
The inverting input of the error amplifier. Tie to an external resistive divider to set the output voltage.
Shutdown Pin. The accurate 1.1V shutdown threshold and the 4.6uA shutdown pin current
hysteresis allow the user to set the undervoltage lockout threshold and hysteresis for the switching
regulator. Pulling this pin below 0.1V causes the converter to shut down to low quiescent current.
Tie this pin to IN if the UVLO and the shutdown features are not used. This pin should not be left
floating.
Ground. Tie both pins to the ground plane. Pins 4 and 5 are not internally connected.
Collector of the internal power transistor. Connect to the boost inductor and the rectifying diode.
Power Supply Pin. Bypassed with capacitors close to the pin.
A resistor from this pin to the ground sets the switching frequency.
Soft-Start Pin. A capacitor from this pin to the ground lengthens the start-up time and reduces start-
up current.
The exposed pad must be soldered to the ground plane on the PCB for good thermal conduction.
3
SHDN
4,5
6,7
8
9
10
GND
SW
IN
ROSC
SS
Exposed Pad
Block Diagram
IN
8
4.6µA
SW SW
6
7
SHDN
3
+
-
1.1V
CMP
INTERNAL
SUPPLY
ENABL E
CLK
REG
VOLTAGE
REFERENCE
THERMAL
SHUTDOWN
FB
2
COMP
1
SS
10
1.242V
+
-
EA
REG
1.5µA
-
R
S
Q
+
PWM
+
ILIM
-
I-LIMIT
REG_GOOD
ENABL E
R
SENSE
Σ
+
+
+
ISEN
-
5
GND GND
4
ROSC
9
CLK
OSCILLATOR
SLOPE COMP
Figure 2. SC4502/SC4502H Block Diagram.
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SC4502/SC4502H
POWER MANAGEMENT
Typical Characteristics
Feedback Voltage vs Temperature
1.3
100
R
OSC
vs Switching Frequency
1.7
Switching Frequency
vs Temperature
R
OSC
= 7.68KΩ
Feedback Voltage (V)
1.25
V
IN
= 2V
R
OSC
(K
Ω
)
25ºC
10
Frequency (MHz)
1.6
V
IN
= 12V
1.5
V
IN
= 2V
1.4
1.2
1.15
-50
-25
0
25
50
75
100
125
1
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1.3
-50
-25
0
25
50
75
100
125
Temperature (ºC)
Frequency (MHz)
Temperature (ºC)
Switch Saturation Voltage
vs Switch Current
500
500
Switch Saturation Voltage
vs Switch Current
1.5
Minimum V
IN
vs Temperature
SC4502
400
400
SC4502H
1.4
300
300
Input Voltage (V)
1.5
2
V
CESAT
(mV)
V
CESAT
(mV)
1.3
85ºC
200
85ºC
200
25ºC
100
25ºC
100
1.2
1.1
0
0
0.5
1
1.5
2
0
0
0.5
1
1
-50
-25
0
25
50
75
100
125
Switch Current (A)
Switch Current (A)
Temperature (ºC)
V
IN
Quiescent Current vs Temperature
1.3
50
V
IN
Current in Shutdown
vs Input Voltage
1.20
Shutdown Threshold
vs Temperature
V
IN
= 2V
Shutdown Threshold (V)
Not Switching
1.2
40
1.15
V
IN
Current (mA)
1.1
V
IN
Current (
µ
A)
V
IN
= 16V
-40ºC
30
125ºC
20
1.10
1
V
IN
= 2V
0.9
10
V
SHDN
= 0
1.05
0.8
-50
-25
0
25
50
75
100
125
0
0
5
10
15
20
1.00
-50
-25
0
25
50
75
100
125
Temperature (ºC)
Input Voltage (V)
Temperature (ºC)
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