Application Note: AN_SY8120B
High Efficiency Fast Respon, 2A, 18V Input Synchronous Step Down Regulator Preliminary Specification General Description
SY8120B develops high efficiency synchronous stepdown DC-DC converter capable of delivering 2A load current . SY8120B operates over a wide input voltage range from 4.5V to 18V and integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. SY8120B adopts the instant PWM architecture to achieve fast transient respons for high step down applications and high efficiency at light loads. In addition, it operates at pudo-constant frequency of 500 kHz under heavy load conditions to minimize the size of inductor and capacitor.
Features
• Low RDS(ON) for internal switches (top/bottom):145/135 mΩ • 4.5-18V input voltage range • 2A load current capability • Instant PWM architecture to achieve fast transient respons Internal softstart limits the inrush current • 2% 0.6V reference • RoHS Compliant and Halogen Free • Compact package: SOT23-6
Ordering Information
SY8120 □(□□)□ Temperature Code Package Code Optional Spec Code Temperature Range: -40°C to 85°C Ordering Number SY8120BABC Package type SOT23-6 Note --
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Typical Applications
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Figure 1. Schematic Diagram
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Efficiency (%)
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• • • • •
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AN_SY8120B Rev.0.2
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Applications
Figure 2. Efficiency Figure
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Pinout (top view)
(SOT23-6) Top Mark: NBxyz, (Device code: NB, x=year code, y=week code, z= lot number code)
BS GND FB EN IN LX
1 2 3 4 5 6
Recommended Operating Conditions (Note 3)
Supply Input Voltage ----------------------------------------------------------------------------------------- 4.5V to 18V Junction Temperature Range -------------------------------------------------------------------------------- -40°C to 125°C Ambient Temperature Range --------------------------------------------------------------------------
------ -40°C to 85°C
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AN_SY8120B Rev.0.2
测试化验加工费
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Supply Input Voltage ----------------------------------------------------------------------------------------- 19V LX, EN Voltage------------------------------------------------------------------------------------------------ VIN + 0.3V FB, BS-LX Voltage--------------------------------------------------------------------------------------------- 4V Power Dissipation, PD @ TA = 25°C SOT23-6, ----------------------------------------------------------- 0.6W Package Thermal Resistance (Note 2) θ JA ---------------------------------------------------------------------------------------------------- 170°C/W θ JC ---------------------------------------------------------------------------------------------------- 130°C/W Junction Temperature Range -------------------------------------------------------------------------------- 125°C Lead Temperature (Soldering, 10 c.) -------------------------------------------------------------------- 260°C Storage Temperature Range --------------------------------------------------------------------------------- -65°C to 150°C
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Absolute Maximum Ratings (Note 1)
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Pin Name
Pin Number
Pin Description Boot-Strap Pin. Supply high side gate driver. Decouple this pin to LX pin with 0.1uF ceramic cap. Ground pin 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. 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
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Electrical Characteristics
(VIN = 12V, VOUT = 1.2V, L = 2.2uH, COUT = 10uF, TA = 25°C, IOUT = 1A unless otherwi specified)
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Parameter Input Voltage Range Quiescent Current Shutdown Current Feedback Reference Voltage FB Input Current Top FET RON Bottom FET RON Bottom FET Valley Current Limit EN Rising Threshold EN Falling Threshold Input UVLO Threshold On Time Min ON Time Min Off Time Thermal Shutdown Temperature Thermal Shutdown Hysteresis
Symbol VIN IQ ISHDN VREF IFB RDS(ON)1 RDS(ON)2 ILIM VENH VENL VUVLO TON
Test Conditions IOUT=0, VFB=VREF×105% EN=0
Min 4.5
Typ 400 5 0.6
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0.588 VFB=VIN -50
Unit V µA µA V nA Ω Ω A
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0.145 0.135
TSD THYS
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VIN = 12V ,VOUT=1.2V, IOUT = 1A
V V V ns ns ns °C °C
Note 2: θ JA is measured in the natural convection at TA = 25°C on a low effective single layer therm
al conductivity test board of JEDEC 51-3 thermal measurement standard. Pin 2 of SOT-23-6 packages is the ca position for θ JC measurement. Note 3: The device is not guaranteed to function outside its operating conditions.
AN_SY8120B Rev.0.2
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Note 1: Stress listed as the above “Absolute Maximum Ratings” may cau permanent damage to the device. The are for stress ratings. Functional operation of the device at the or any other con
ditions beyond tho indicated in the operational ctions of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability.
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Typical Performance Characteristics
Efficiency (%)
Efficiency (%)
AN_SY8120B Rev.0.2
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AN_SY8120B
Short Circuit Protection
(VIN=12V, VOUT=3.3V, Open to Short)
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VOUT
VOUT
2V/div
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1A/div
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Time (2ms/div)
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AN_SY8120B Rev.0.2
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薄藤色
100毫米
Silergy Corp. Confidential-prepared for Internal U Only
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Short Circuit Protection
(VIN=12V, VOUT=3.3V, 2A to Short)
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2V/div 1A/div
Time (2ms/div)
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