Application Notes: AN_SY8113G
High Efficiency, 500kHz, 3A, 18V Input
Synchronous Step Down Regulator
General Description
The SY8113G is a high efficiency 500 kHz
synchronous step-down DC-DC converter capable of
delivering 3A current. The SY8113G 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.
SY8113G always operates under continuous condition
mode, low output ripple and small inductor and
capacitor size are achieved with 500kHz switching
frequency.
Features
low R
DS(ON)
for internal switches (top/bottom):
80mΩ/40mΩ
4.5-18V input voltage range
3A output current capability
500 kHz switching frequency
Instant PWM architecture to achieve fast transient
responses.
Cycle-by-cycle peak current limitation
Internal softstart limits the inrush current
±1.5%
0.6V reference
TSOT23-6 package
Ordering Information
SY8113
□
(
□□
)
□
Typical Applications
C
1
Co
rp
.C
on
fid
en
Ordering Number
SY8113GADC
Package type
TSOT23-6
Note
--
tia
Temperature Code
Package Code
Optional Spec Code
l-P
Set Top Box
Portable TV
Access Point Router
DSL Modem
LCD TV
re
Applications
y
V
IN
BS
L
1
V
OUT
Efficiency (%)
IN
LX
C
OUT
rg
le
C
IN
SY8113G
R
1
C
4
pa
re
100
90
80
70
60
50
40
30
20
10
0
0.001
d
0.01
Efficiency vs. Load Current
fo
r
Si
ON/
OFF
EN
GND
FB
R
2
M
0.1
TC
V
IN
=5V,V
OUT
=3.3V
V
IN
=12V,V
OUT
=3.3V
V
IN
=18V,V
OUT
=3.3V
1
Load Current (A)
Figure 1. Schematic Diagram
Figure2. Efficiency vs. Load Current
AN_SY8113G Rev.0.9A
© 2018 Silergy Corp.
Silergy Corp. Confidential-prepared for Customer Use Only
1
All Rights Reserved.
SY8113G
Pinout
(
top view)
BS
GND
FB
LX
IN
EN
TSOT23-6
Top Mark:
Itxyz
,
(Device
code: It,
x=year code, y=week code, z= lot number code)
GND
FB
2
3
EN
IN
LX
4
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
Recommended Operating Conditions
(Note 3)
Supply Input Voltage ---------------------------------------------------------------------------------------------- 4.5V to 18V
Junction Temperature Range --------------------------------------------------------------------------------- -40° to 125°
C
C
Ambient Temperature Range ----------------------------------------------------------------------------------
-
40° to 85°
C
C
AN_SY8113G Rev.0.9A
© 2018 Silergy Corp.
Si
le
rg
Supply Input Voltage --------------------------------------------------------------------------------------------------------- 19V
Enable Voltage-------------------------------------------------------------------------------------------------------- VIN + 0.3V
FB Voltage ---------------------------------------------------------------------------------------------------------------------- 4V
Power Dissipation, PD @ TA = 25° TSOT23-6 ---------------------------------------------------------------------- 1.5W
C,
Package Thermal Resistance (Note 2)
θ
JA ----------------------------------------------------------------------------------------------------------------- 66° /W
C
θ
JC ----------------------------------------------------------------------------------------------------------------- 15° /W
C
Junction Temperature Range -------------------------------------------------------------------------------------------- 150°
C
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------- 260°
C
Storage Temperature Range ----------------------------------------------------------------------------------- -65° to 150°
C
C
y
Co
rp
.C
on
Absolute Maximum Ratings
(Note 1)
Silergy Corp. Confidential-prepared for Customer Use Only
2
All Rights Reserved.
fid
en
tia
l-P
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.
re
pa
re
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
d
fo
r
M
TC
SY8113G
Electrical Characteristics
(V
IN
= 12V, V
OUT
= 1.2V, L = 2.2uH, C
OUT
= 47uF, T
A
= 25° I
OUT
= 1A unless otherwise specified)
C,
Note 2:
θ
JA is measured in the natural convection at T
A
= 25° on a two-layer Silergy Evaluation Board.
C
Note 3:
The device is not guaranteed to function outside its operating conditions
AN_SY8113G Rev.0.9A
© 2018 Silergy Corp.
Si
le
rg
y
Co
rp
.C
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.
on
Silergy Corp. Confidential-prepared for Customer Use Only
3
All Rights Reserved.
fid
Parameter
Input Voltage Range
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
5.8
4
re
V
ENH
V
ENL
V
UVLO
V
HYS
pa
re
d
I
LIM
fo
r
4.2
0.3
60
170
500
800
150
15
I
FB
R
DS(ON)1
R
DS(ON)2
I
LIM,TOP
M
80
40
V
FB
=3.3V
-50
TC
50
90
50
6.6
5.2
0.4
4.5
100
220
Symbol
V
IN
I
SHDN
V
REF
Test Conditions
EN=0
Min
4.5
0.591
Typ
5
0.6
Max
18
10
0.609
Unit
V
µA
V
nA
mΩ
mΩ
A
A
V
V
V
V
ns
ns
kHz
uS
°
C
°
C
1.5
3.8
40
140
t
SS
T
SD
T
HYS
en
tia
l-P
SY8113G
Block Diagram
IN
Current Sense
EN
1.5V
l-P
FB
0.6V
Internal
SST
Thermal
Protection
en
tia
re
pa
re
Current Sense
PWM
Control &
Protect
Logic
d
fo
r
LX
GND
Internal
Power
Input
UVLO
4.5V
AN_SY8113G Rev.0.9A
© 2018 Silergy Corp.
Si
le
rg
y
Co
rp
.C
on
Silergy Corp. Confidential-prepared for Customer Use Only
4
All Rights Reserved.
fid
M
TC
BS
SY8113G
Typical Performance Characteristics
Efficiency vs. Load Current
100
90
80
100
90
80
Efficiency vs. Load Current
Efficiency (%)
Efficiency (%)
70
60
50
40
30
20
10
0
0.001
0.01
0.1
1
V
IN
=5V,V
OUT
=1.2V
V
IN
=12V,V
OUT
=1.2V
V
IN
=18V,V
OUT
=1.2V
70
60
50
40
30
20
10
0
0.001
fo
r
d
0.01
M
V
IN
=5V,V
OUT
=3.3V
V
IN
=12V,V
OUT
=3.3V
V
IN
=18V,V
OUT
=3.3V
0.1
1
Load Current (A)
pa
re
re
l-P
tia
en
1
Load Current (A)
Efficiency vs. Load Current
100
90
80
Output Ripple
(V
IN
=12V, V
OUT
=3.3V, I
OUT
=0A)
ΔV
OUT
10mV/div
Efficiency (%)
70
60
50
40
30
20
10
0
0.001
0.01
V
LX
10V/div
Co
rp
.C
0.1
on
V
IN
=7.4V,V
OUT
=5V
V
IN
=12V,V
OUT
=5V
V
IN
=18V,V
OUT
=5V
fid
I
L
1A/div
Load Current (A)
Time (2μs/div)
Output Ripple
rg
y
(V
IN
=12V, V
OUT
=3.3V, I
OUT
=3A)
ΔV
OUT
V
LX
20mV/div
10V/div
Si
le
I
L
2A/div
Time (2μs/div)
AN_SY8113G Rev.0.9A
© 2018 Silergy Corp.
Silergy Corp. Confidential-prepared for Customer Use Only
5
All Rights Reserved.
TC
FPGA/CPLD
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