Application Notes: AN_SY8113C
High Efficiency, 1MHz, 3A, 18V Input
Synchronous Step Down Regulator
General Description
The SY8113C is a high efficiency 1MHz synchronous
step-down DC-DC converter capable of delivering 3A
current. The SY8113C operates over a wide input
voltage range from 4.5V to 18V and integrates main
switch and synchronous switch with very low R
DS(ON)
to minimize the conduction loss.
Low output voltage ripple and small external inductor
and capacitor sizes are achieved with 1MHz switching
frequency. It adopts the instant PWM architecture to
achieve fast transient responses for high step down
applications.
Features
•
•
•
•
•
•
•
•
low R
DS(ON)
for internal switches (top/bottom):
80mΩ/40mΩ
4.5-18V input voltage range
3A output current capability
1MHz switching frequency
Instant PWM architecture to achieve fast transient
responses.
Internal softstart limits the inrush current
±1.5%
0.6V reference
TSOT23-6 package
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Typical Applications
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Ordering Number
SY8113CADC
Package type
TSOT23-6
Note
--
re
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100
80
60
40
Temperature Code
Package Code
Optional Spec Code
re
0
0.1
SY8113
□
(
□□
)
□
•
•
•
•
•
Set Top Box
Portable TV
Access Point Router
DSL Modem
LCD TV
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Ordering Information
Applications
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Efficiency vs. Load Current
V
IN
=5V,V
OUT
=3.3V
V
IN
=12V,V
OUT
=3.3V
V
IN
=18V,V
OUT
=3.3V
1
10
100
gy
20
Sil
er
r双
翼
1000
Load Current (mA)
Figure 1. Schematic Diagram
Figure2. Efficiency vs. Load Current
SY8113C Rev.0.1A
Silergy Corp. Confidential-prepared for Internal Use Only
1
SY8113C
Pinout
(
top view)
BS
LX
GND
IN
FB
EN
TSOT23-6(FC)
IN
LX
5
6
Input pin. Decouple this pin to GND pin with at least 1uF ceramic cap
Inductor pin. Connect this pin to the switching node of inductor
Absolute Maximum Ratings
(Note 1)
Supply Input Voltage ------------------------------------------------------------------------------------ 4.5V to 18V
Junction Temperature Range ----------------------------------------------------------------------- -40°C to 125°C
Ambient Temperature Range ------------------------------------------------------------------------
-
40°C to 85°C
SY8113C Rev.0.1A
Sil
er
Recommended Operating Conditions
(Note 3)
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Supply Input Voltage ------------------------------------------------------------------------------------------------ 19V
Enable Voltage---------------------------------------------------------------------------------------------- VIN + 0.3V
FB Voltage ----------------------------------------------------------------------------------------------------------- 4V
Power Dissipation, PD @ TA = 25°C, TSOT23-6（FC）----------------------------------------------------- 1W
Package Thermal Resistance (Note 2)
θ
JA ------------------------------------------------------------------------------------------------------ 100°C /W
θ
JC ----------------------------------------------------------------------------------------------------- 11.2°C /W
Junction Temperature Range ----------------------------------------------------------------------------------- 150°C
Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------- 260°C
Storage Temperature Range ------------------------------------------------------------------------- -65°C to 150°C
p.
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Silergy Corp. Confidential-prepared for Internal Use Only
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EN
4
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FB
3
Output Feedback Pin. Connect this pin to the center point of the output resistor
divider (as shown in Figure 1) to program the output voltage:
Vout=0.6*(1+R1/R2)
Enable control. Pull high to turn on. Do not float.
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GND
2
r双
Pin Name
BS
Pin Number
1
Pin Description
Boot-Strap Pin. Supply high side gate driver. Decouple this pin to LX pin with
0.1uF ceramic cap.
Ground pin
翼
Top Mark:
WDxyz
,
(Device
code: WD,
x=year code, y=week code, z= lot number code)
2
SY8113C
Electrical Characteristics
(V
IN
= 12V, V
OUT
= 3.3V, L = 2.2uH, C
OUT
= 47uF, T
A
= 25°C, I
OUT
= 1A unless otherwise specified)
T
HYS
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Parameter
Input Voltage Range
Quiescent Current
Shutdown Current
Feedback Reference
Voltage
FB Input Current
Top FET RON
Bottom FET RON
Top FET Peak Current
Limit
Bottom FET Valley
Current Limit
EN Rising Threshold
EN Falling Threshold
Input UVLO Threshold
UVLO Hysteresis
Min ON Time
Min OFF Time
Switching Frequency
Soft-start Time
Thermal Shutdown
Temperature
Thermal Shutdown
Hysteresis
Symbol
V
IN
I
Q
I
SHDN
V
REF
I
FB
R
DS(ON)1
R
DS(ON)2
I
LIM,TOP
I
LIM
V
ENH
V
ENL
V
UVLO
V
HYS
Test Conditions
I
OUT
=0
,
V
FB
=V
REF
*105%
EN=0
Min
4.5
Typ
100
5
0.6
Max
18
10
0.609
50
90
50
6.6
5.2
0.591
V
FB
=3.3V
-50
Unit
V
µA
µA
V
nA
mΩ
mΩ
A
A
V
V
V
V
ns
ns
MHz
us
°C
°C
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4
1.5
40
140
0.3
60
170
1
800
150
15
翼
80
40
0.4
4.5
90
220
t
SS
T
SD
Note 2:
θ
JA is measured in the natural convection at T
A
= 25°C on a low effective 4-layer thermal conductivity test
board of JEDEC 51-3 thermal measurement standard.
Note 3:
The device is not guaranteed to function outside its operating conditions
AN_SY8113C Rev.0.1A
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Note 1:
Stresses beyond the “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
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Silergy Corp. Confidential-prepared for Internal Use Only
3
SY8113C
Block Diagram
AN_SY8113C Rev.0.1A
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Silergy Corp. Confidential-prepared for Internal Use Only
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r双
翼
4
SY8113C
Typical Performance Characteristics
Efficiency vs. Load Current
100
90
80
70
60
50
40
30
20
10
0
0.1
1
10
100
1000
0
0.1
1
V
IN
=5V,V
OUT
=1.2V
V
IN
=12V,V
OUT
=1.2V
V
IN
=18V,V
OUT
=1.2V
40
V
IN
=5V,V
OUT
=3.3V
V
IN
=12V,V
OUT
=3.3V
20
V
IN
=18V,V
OUT
=3.3V
60
80
100
Efficiency vs. Load Current
r双
10
翼
100
1000
Load Current (mA)
Load Current (mA)
Efficiency vs. Load Current
100
90
80
70
60
50
40
30
20
10
0
0.1
1
10
V
IN
=8V,V
OUT
=5V
V
IN
=12V,V
OUT
=5V
V
IN
=18V,V
OUT
=5V
100
Load Current (mA)
AN_SY8113C Rev.0.1A
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Silergy Corp. Confidential-prepared for Internal Use Only
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1000
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FPGA/CPLD
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