Application Note: SY8286A
High Efficiency Fast Response
6A, 23V Input Synchronous Step Down Regulator
General Description
The SY8286A develops a high efficiency synchronous
step-down DC-DC regulator capable of delivering 6A
current. The device integrates main switch and
synchronous switch with very low R
DS(ON)
to minimize
the conduction loss.
The SY8286A operates over a wide input voltage range
from 4V to 23V. The DC-DC regulator adopts the instant
PWM architecture to achieve fast transient responses for
high step down applications and high efficiency at light
load. The device provides various protection features for
reliable operation. In addition, it operates at pseudo-
constant frequency of 600kHz to minimize the size of
inductor and capacitor.
Features
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Low R
DS(ON)
for internal switches (top/bottom):
38/19 mΩ
Wide input voltage range: 4-23V
Instant PWM architecture to achieve fast transient
responses
Internal 1.3ms soft-start limits the inrush current
Pseudo-constant frequency: 600kHz.
6A output current capability
+/-1% internal reference voltage
PFM/PWM selectable light l ad peration mode
Optional bypass input
Power good indicator
Output discharge function
Output current limit protection
Hiccup mode output short circuit protection
Output over voltage protection
Input UVLO
Ov r t mperature protection with auto recovery
RoHS Compliant and Halogen Free
Compact package: QFN3x3-20
Ordering Information
SY8286
□
(
□□
)
□
Temperature Code
Package Code
Optional Spec Code
Ordering Number
SY8286ARAC
Package type
QFN3x3-20
Note
--
Applications
•
•
•
•
LCD-TV/Net-TV/3DTV
Set Top Box
Notebook
High Power AP
Typical Applications
Figure 1 Schematic
AN_SY8286A Rev. 0.9C
Silergy Corp. Confidential- Prepared for Customer Use Only
1
SY8286A
Pinout
(
top view)
Top
Pin Name
BS
IN
LX
GND
PG
NC
EN
MODE
ILMT
FB
BYP
VCC
(QFN3x3-20)
Mark: AWR
xyz
,
(Device
code: AWR,
x=year code, y=week code, z= lot number code)
Pin Number
1
2,3,4,5
6,19,20
7,8,18,EP
9
10, 16
11
12
13
14
15
17
Pin Description
Boot-strap pin. Supply high side gate driver. Decouple this pin to LX pin with
0.1uF ceramic capacitor.
Input pin. Decouple this pin to GND pin with at least 10uF ceramic cap
Inductor pin. Connect this pin to the switching node of inductor
Ground pin
Power good Indicator. Open drain output when the output voltage is within 90% to
120% of regulation point.
Not connected
Enable pin. Pull this pin high to turn on IC. Do not leave this pin floating.
Operating mode selection under light load. Pull this pin low for PFM operating,
and pull this pin high for PWM operation. Do not leave this pin floating
Output current limit threshold selection.
Output feedback pin. Connect to the center point of resistor divider.
External 3.3V bypass power supply input. Decouple this pin to GND with a 1uF
ceramic capac tor. Leave this pin floating if it is not used.
Internal 3.3V LDO output. Power supply for internal analog circuits and driving
circuit. Decouple this pin to GND with a 2.2uF ceramic capacitor.
AN_SY8286A Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only
2
SY8286A
Block Diagram
IN
Input
UVLO
Current Sense
PG
EN
ILMT
MODE
Internal
SST
OTP
0.6V
PWM
Control &
Protection
Logic
Current Sense
BS
LX
GND
FB
IN
BYP
3.1V
3.3V LDO
VCC
Absolute Maximum Ratings
(Note 1)
IN ---------------------------------------------------------------------------------------------------------------------------------
25V
BS-LX -----------------------------------------------------------------------------------------------------------
4V
EN, ILMT, MODE, PG, LX --------------------------------------------------------------------------------------------------
25V
VCC, FB -----------------------------------------------------------------------------------------------------------
4V
BYP ---------------------------------------------------------------------------------------------------------
6V
Power Dissipation,
P
D
@ T
A
= 25°C QFN3x3-20 -------------------------------------------------------------------------------------
3.3W
Package Thermal Resistance (Note 2)
θ
JA
, QFN3x3-20 ------------------------------------------------------------------------------------------------
30°C/W
θ
JC
, QFN3x3-20 -----------------------------------------------------------------------------------------------
4.5°C/W
Junction Temperature Range ------------------------------------------------------------------------------------------------
150°C
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------------
260°C
Storage Temperature Range --------------------------------------------------------------------------------------
-65°C to 150°C
Dynamic LX voltage in 10ns duration ---------------------------------------------------------------------
IN+3V to GND-5V
Recommended Operating Conditions
(Note 3)
Supply Input Voltage ----------------------------------------------------------------------------------------------------
4V to 23V
Junction Temperature Range ------------------------------------------------------------------------------------- - 40°C to 125°C
Ambient Temperature Range --------------------------------------------------------------------------------------
-40°C to 85°C
AN_SY8286A Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only
3
SY8286A
Electrical Characteristics
Parameter
Input Voltage Range
Input UVLO Threshold
UVLO hysteresis
Quiescent Current
Shutdown Current
Feedback Reference
Voltage
Top FET RON
Bottom FET RON
Output Discharge Current
Top FET Current Limit
Bottom FET Current
Limit
Soft Start Time
EN/MODE Rising
Threshold
EN/MODE Falling
Threshold
ILMT Rising Threshold
ILMT Falling Threshold
Switching Frequency
Min ON Time
Min OFF Time
VCC Output Voltage
Output Over Voltage
Threshold
Output Over Voltage
Hysteresis
Output OVP Delay
Output Under Voltage
Protection Threshold
Output UVP Delay
Power Good Threshold
Power Good Hysteresis
Power Good Delay
Bypass Switch Turn -on
Voltage
Bypass Switch
Switchov r Hysteresis
Bypass Switch OVP
Thermal Shutdown
Temperature
Thermal Shutdown
hysteresis
V
V
I
(V
IN
= 12V, T
A
= 25°C unless otherwise specified)
Symbol
IN
Test Conditions
V
IN
Rising
I
OUT
=0
,
V
OUT
=V
SET
*105%
EN=0,
V
Min
4
Typ
UVLO
Max
23
3.9
145
10
0.606
HYS
I
Q
V
SHDN
REF
0.594
0.1
120
6
0.6
38
19
70
17
7.8
10.6
13.3
1.3
Unit
V
V
V
µA
µA
V
mΩ
mΩ
mA
A
A
A
A
ms
V
V
V
V
kHz
ns
ns
V
%V
%V
R
DS(ON)1
R
DS(ON)2
I
DIS
I
LMT,HSFET
I
LMT, LSFET
t
ILMT=Low
ILMT=Floating
ILMT=High
6.7
9.3
12
1
8.9
11.9
14.8
V
V
SS
ENH
ENL
0.4
Vcc-0.5
V =V
IN
V
ILMTH
V
ILMTL
F
OSC
T
ON,MIN
T
OFF,MIN
V
510
INMAX
V
V
t
CC
OVP
With 1mA Lo d
V
FB
Rising
3.2
115
600
50
150
3.3
120
1.5
20
62.5
200
92
1.5
200
10
3.1
0.15
120
150
15
0.5
690
3.4
125
REF
OVP,HYS
REF
V
OVP,DLY
UVP
V
FB
Falling
V
FB
Rising (Good)
Low to high
High to low
57.5
67.5
µs
%V
us
REF
t
UVP,DLY
V
PG
V
PG,HYS
t
PG,RISING
t
%V
REF
%V
REF
V
V
V
PG,FALLING
BYP
2.97
3.21
µs
µs
V
V
%V
CC
°C
°C
BYP,HYS
T
BYP,OVP
SD
T
HYS
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
AN_SY8286A Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only
4
SY8286A
operational sections of the specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability
Note 2:
Package thermal resistance is measured in the natural convection at T
A
= 25°C on a four-layer Silergy
Evaluation Board.
Note 3:
The device is not guaranteed to function outside its operating conditions.
AN_SY8286A Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only
5
Microchip MCU
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