Application Note:
SY7069
5.5V Maximum Output, 3A Valley Current, 1MHz
Synchronous Boost with Auto Bypass Function
General Description
SY7069 is a high efficiency, synchronous, step-up
boost converter designed for one-cell Li-Ion or Li-
polymer, or a two to three-cell alkaline Ni-Cd or Ni-
MH battery powered applications. It can convert down
to 2.5V input voltage and up to 5.5V output voltage. It
adopts NMOS for the main switch and PMOS for the
synchronous switch.
SY7069 can disconnect the output from input during
the shutdown mode. When input voltage exceeds the
regulated output voltage, SY7069 enters bypass mode
automatically.
Features
2.5V minimum input voltage
Adjustable output voltage from 2.5V to 5.5V
Min 3A valley current limit
Capable for seamless transition between boost and
bypass mode
Load disconnect during shutdown
Low R
DS(ON)
(main switch/synchronous switch) at
5.0V output: 50mΩ/90mΩ
Output OVP protection
Compact package TSOT23-6 package
Applications
Ordering Information
SY7069
□(□□)□
Temperature Code
Package Code
Optional Spec Code
Package type
TSOT23-6
Note
----
All Single Cell Li or Dual Cell Battery Operated
Products as MP-3 Player, PDAs, and Other
Portable Equipment.
Ordering Number
SY7069ADC
Typical Applications
Figure 1. Schematic Diagram
AN_SY7069 Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
1
SY7069
Pinout (top view)
FB
IN
GND
1
2
3
6
5
4
EN
LX
OUT
(TSOT23-6)
Top mark:
Iexyz
(Device cod
e: Ie
,
x=year code, y=week code, z= lot number code)
Name
FB
IN
GND
OUT
LX
EN
TSOT23-6
1
2
3
4
5
6
Description
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: V
OUT
=1.2× (1+R
H
/R
L
).
Signal input pin. Decouple this pin to GND pin with at least 1uF ceramic cap for noise
immunity consideration.
Ground pin.
Output pin. Decouple this pin to GND pin with at least 22µF ceramic cap.
Inductor node. Connect an inductor between IN pin and LX pin.
Enable pin. Pull high to turn on. Do not leave it floating.
Absolute Maximum Ratings
(Note 1)
All Pins------------------------------------------------------------------------------------------------------------------------------- -- 6.0V
Power Dissipation, P
D
@ T
A
=25°C, TSOT23-6----------------------------------------------------------------------------- --1.92W
Package Thermal Resistance (Note 2)
θ
JA----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
52°C/W
θ
JC----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
32°C/W
Junction Temperature Range------------------------------------------------------------------------------------------------------ 150°C
Lead Temperature (Soldering, 10 sec.)------------------------------------------------------------------------------------------260°C
Storage Temperature Range-------------------------------------------------------------------------------------------- 65°C to 150°C
Recommended Operating Conditions
(Note 3)
IN------------------------------------------------------------------------------------------------------------------------------ 2.5V to 5.5V
OUT------------------------------------------------------------------------------------------------------------------------ -- 2.5V to 5.5V
EN, FB-------------------------------------------------------------------------------------------------------------------- V to V
OUT
+0.3V
All other pins------------------------------------------------------------------------------------------------------------------------ 0-5.5V
Junction Temperature Range--------------------------------------------------------------------------------------------40°C to 125°C
Ambient Temperature Range---------------------------------------------------------------------------------------------40°C to 85°C
AN_SY7069 Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
2
SY7069
Electrical Characteristics
(V
IN
=3.0V, V
OUT
=5.0V, I
OUT
=500mA, T
A
= 25°C unless otherwise specified)
Parameter
Symbol
Test Conditions
V
IN
Input Voltage
V
OUT
Output Voltage Range
V
IN
Quiescent
I
Q
Io=0A,V
EN
=V
IN
=3.0V,
V
OUT
Current
V
OUT
=5.0V,V
FB
=105%V
REF
I
SHDN
Shutdown Current
V
EN
=0V, V
IN
=3.0V
I
CHARGE
Linear Charge Current
V
OUT
<0.5V
IN
V
UVLO
Input Vin UVLO Threshold
V
SYS
V
IN
UVLO Hysteresis
V
ENH
EN Rising Threshold
V
ENL
EN Falling Threshold
R
DS(ON)1
Low Side Main FET R
ON
V
OUT
=5.0V
R
DS(ON)2
Synchronous FET R
ON
V
OUT
=5.0V
I
LIM
Synchronous FET Current
Limit
Switching Frequency
Fsw
V
REF
Feedback Reference Voltage
T
ON_MIN
Minimum on time
T
OFF_MIN
Minimum off time
OUT pin OVP Protection
OUT pin OVP Hysteresis
OVP
HYS
T
SD
Thermal Shutdown
Temperature
T
HYS
Thermal Shutdown Hysteresis
Min
2.5
2.5
Typ
8
32
0.1
1.5
0.1
50
90
1.0
1.2
80
80
6.0
0.25
150
20
Max
5.5
5.5
1
2.5
0.4
Unit
V
V
µA
µA
µA
A
V
V
V
V
mΩ
mΩ
A
MHz
V
ns
ns
V
V
°C
°C
1.2
3.0
1.182
1.218
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 may affect
device reliability.
Note 2:
θ
JA is measured in the natural convection at T
A
= 25°C on a two-layer Silergy Evaluation Board.
Note 3:
The device is not guaranteed to function outside its operating conditions.
Block Diagram
AN_SY7069 Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
3
SY7069
Typical Performance Characteristics
Efficiency vs. Load Current
100
98
96
95
94
92
90
85
88
86
84
82
0
0.5
1
1.5
2
2.5
3
V
IN
=2.7V,V
OUT
=5V
V
IN
=3.3V,V
OUT
=5V
V
IN
=4.2V,V
OUT
=5V
Efficiency vs. Load Current
90
80
V
IN
=2.7V,V
OUT
=3.6V
V
IN
=3.3V,V
OUT
=3.6V
75
0
0.5
1
1.5
2
2.5
3
Load Current (A)
Load Current (A)
Max Load Current vs. V
IN
3.5
Load Transient
(V
IN
=3.3V,V
OUT
=5V,Io=0.1A~1A)
3.0
∆V
OUT
500mV/div
2.5
2.0
V
OUT
=3.6V
V
OUT
=5.0V
I
L
1A/div
1.5
1.0
2.5
3.0
3.5
4.0
4.5
V
IN
(V)
Time (100µs/div)
Startup from Enable
(V
IN
=3.3V,V
OUT
=5V,Io=1A)
Shutdown from Enable
(V
IN
=3.3V,V
OUT
=5V,Io=1A)
V
EN
V
OUT
V
LX
2V/div
5V/div
5V/div
V
EN
V
OUT
V
LX
2V/div
5V/div
5V/div
I
L
2A/div
I
L
2A/div
Time (100µs/div)
Time (100µs/div)
AN_SY7069 Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
4
SY7069
Short Circuit Protection
(V
IN
=3.3V,V
OUT
=5V,0A to Short)
Short Circuit Protection
(V
IN
=3.3V,V
OUT
=5V,1A to Short)
V
OUT
5V/div
V
OUT
5V/div
I
L
1A/div
I
L
1A/div
Time (20ms/div)
Time (20ms/div)
Seamless Transition: Boost Mode→Bypass Mode
(V
IN
=3.3V~5.5V, V
OUT
=5.0V, Io=1.0A)
V
IN
Seamless Transition: Bypass Mode→Boost Mode
(V
IN
=5.5V~3.3V, V
OUT
=5.0V, Io=1.0A)
2V/div
2V/div
5V/div
V
OUT
V
IN
V
LX
2V/div
2V/div
5V/div
V
OUT
V
LX
I
L
1A/div
I
L
1A/div
Time (10ms/div)
Time (10ms/div)
Output Ripple
(V
IN
=3.3V,V
OUT
=5V,Io=1A)
∆V
OUT
50mV/div
V
LX
2V/div
I
L
1A/div
Time (1µs/div)
AN_SY7069 Rev. 0.9
Silergy Corp. Confidential- Prepared for Customer Use Only
5
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