Document
Application Note: AN_SY8089/SY8089A
High Efficiency 5.5V, 2A continuous, 3A peak, 1MHz Synchronous Step Down Regulator
General Description
The SY8089 and SY8089A are high-efficiency, high frequency synchronous step-down DC-DC regulator IC capable of delivering up to 2A output current. The SY8089 and SY8089A operate over a wide input voltage range from 2.7V to 5.5V and integrate main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss.
Low output voltage ripple and small external inductor and capacitor sizes are achieved with greater than 1MHz switching frequency.
SY8089 integrates short circuit and over-voltage latch off protection.
Ordering Information
SY8089 □(□□)□ Temperature Code
Package Code
Optional Spec Code
Temperature Range: -40°C to 85°C
Ordering Number Package type
SY8089AAC
SOT23-5
SY8089AAAC
SOT23-5
Note
Features
• Low RDS(ON) for internal switches (top/bottom):110mΩ/80mΩ
• 2.7-5.5V input voltage range • 2A continuous, 3A peak load current capability • 1MHz switching frequency minimizes the external
components • Internal softstart limits the inrush current • Reliable short circuit protection:
SY8089: Latch off protection SY8089A: Hic-cup mode protection • Reliable over-voltage protection: SY8089: Latch off protection SY8089A: No latch off protection • 100% dropout operation • RoHS Compliant and Halogen Free • Compact package: SOT23-5
Applications
• LCD TV • Set Top Box • Net PC • Mini-Notebook PC • Access Point Router
Typical Applications
EfficiencyChipSP(%)ARK.com
VIN: 2.7-5.5V 4 IN
3 L1:2.2µH LX
VOUT: 1.8V
ON/ OFF
CIN 22µF
1
FB 5 EN
GND 2
R1 200k
C1 COUT 22pF 22µFх2
R2 100k
Figure 1.Schematic diagram
Figure 2. Efficiency vs Load Current
AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 1
Pinout (top view)
SY8089/8089A
Pin Name EN GND LX IN FB
SOT23-5
Part Number
Package type
Top Mark①
SY8089AAC
SOT23-5
JXxyz
SY8089AAAC
SOT23-5
KVxyz
Note① : x=year code, y=week code, z= lot number code
Pin Number 1 2 3 4 5
Pin Description Enable control. Pull high to turn on. Do not float. Ground pin. Inductor pin. Connect this pin to the switching node of inductor. Input pin. Decouple this pin to GND pin with at least 10µF ceramic cap. 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).
Absolute Maximum Ratings (Note 1)
Supply Input Voltage ----------------------------------------------------------------------------------------------- -0.3V to 6.0V Enable, FB Voltage------------------------------------------------------------------------------------------ -0.3V to VIN + 0.6V Power Dissipation, PD @ TA = 25°C,
SOT23-5 -------------------------------------------------------------------------------------------------------------- 0.6W Package Thermal Resistance (Note 2)
θ JA --------------------------------------------------------------------------------------------------------------- 170°C/W θ JC ----------------------------------------------------------------------------------------------------------------130°C/W Junction Temperature Range ----------------------------------------- ------------------------------------------ -40°C to 150°C
Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------------------- 260°C
Storage Temperature Range ------------------------------------------------------------------------------------- -65°C to 150°C
Recommended Operating Conditions (Note 3)
Supply Input Voltage ------------------------------------------------------------------------------------------------ 2.7V to 5.5V
Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------------------- -40°C to 85°C
ChipSPARK.com
AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 2
Block Diagram
SY8089/8089A
ChipSPARK.com
(SY8089)
(SY8089A) AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 3
SY8089/8089A
Electrical Characteristics
(VIN = 5V, VOUT = 2.5V, L = 2.2µH, COUT = 22µF, TA = 25°C, unless otherwise specified)
Parameter Input Voltage Range Quiescent Current
Shutdown Current Feedback Reference Voltage FB Input Current PFET RON NFET RON PFET Current Limit EN rising threshold EN falling threshold Input UVLO threshold UVLO hysteresis Oscillator Frequency Short Circuit Protection Latch Off Threshold Min ON Time Max Duty Cycle Soft Start Time Output Discharge Switch On Resistance Thermal Shutdown Temperature
Symbol VIN IQ
ISHDN VREF IFB RDS(ON),P RDS(ON),N ILIM VENH VENL VUVLO VHYS FOSC VSCP
Test Conditions IOUT=0,
VFB=VREF ⋅ 105%
EN=0 VFB=VIN
IOUT=500mA
TSS RDISCH
TSD
Min Typ 2.7
55
0.588 -50
3.5 1.5
0.1 0.6
110 80
0.2 1 0.25
75 1.