SLF12565 | DigiCamel IC Datasheet

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RT7237C RICHTEK | Alldatasheet

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Technical content

Features

zzzzz ±±±±±1.5% High Accuracy Reference Voltage zzzzz 4.5V to 18V Input Voltage Range zzzzz 2A Output Current zzzzz Integrated N-MOSFET Switches zzzzz Current Mode Control zzzzz Fixed Frequency Operation : 800kHz zzzzz Output Adjustable from 0.8V to 12V zzzzz Stable with Low ESR Ceramic Output Capacitors zzzzz Up to 95% Efficiency zzzzz Programmable Soft-Start zzzzz Cycle-by-Cycle Over Current Limit zzzzz Input Under Voltage Lockout zzzzz Output Under Voltage Protection zzzzz Thermal Shutdown Protection zzzzz RoHS Compliant and Halogen Free Marking Information Simplified Application Circuit VIN EN GND BOOT FB SW L VOUT VIN RT7237C SS CSS COMP CC RC CP CBOOTCIN COUT Chip Enable RT7237CH GSPYMDNN RT7253CHGSP : Product Number YMDNN : Date Code

DS7237C-04 November 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Functional Pin Description Pin No. Pin Name Pin Function 1 BOOT Bootstrap for High Side Gate Driver. Connect a 0.1 μF or greater ceramic capacitor from BOOT to SW pins. 2 VIN Power Input. The Input Voltage range is from 4.5V to 18V. Must bypass with a suitable large ceramic capacitor. 3 SW Switch Node. Connect this pin to an external L-C filter. 9 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 5 FB Feedback Input. It is used to regulate the output of the converter to a set value via an external resistive voltage divider.

6 COMP

Compensation Node. COMP is used to compensate the regulation control loop. Connect a series RC network from COMP to GND. In some cases, an additional capacitor from COMP to GND is required. 7 EN Enable Input. A logic high enables the converter; a logic low forces the IC into shutdown mode reducing the supply current to less than 3μA. 8 SS Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from SS to GND to set the soft-start period. A 0.1 μF capacitor sets the soft-start period to 13.5ms.

Ordering Information

Note : Richtek products are : \ RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. \ Suitable for use in SnPb or Pb-free soldering processes. Pin Configurations (TOP VIEW) SOP-8 (Exposed Pad) BOOT VIN SW GND SS EN FB COMP GND 4 5 Package Type SP : SOP-8 (Exposed Pad-Option 2) RT7237C Lead Plating System G : Green (Halogen Free and Pb Free) H : UVP Hiccup

DS7237C-04 November 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Function Block Diagram Operation Internal Regulator Provide internal power for logic control and switch gate drivers. Shutdown Comparator Activate internal regulator once EN input level is higher than the target level. Force IC to enter shutdown mode when the EN input level is lower than 0.4V. Lockout Comparator Activate the current comparator, release lock-out logic, and enable the switches as EN input level is higher than lockout threshold voltage. Otherwise, the switches still lock out. Oscillator The oscillator provides internal clock and controls the converter's switching frequency. Foldback Control Dynamically adjust the internal clock. It provides a slower frequency as a lower FB voltage. UV Comparator As FB voltage is lower than the UV voltage, it will activate a UV protect scheme. Error Amplifier The output voltage COMP of the error amplifier is adjusted by comparing FB signal with the internal reference voltage and SS signal. Current Sense Amplifier R SENSE detects the peak current of the high side switch. This signal is amplified by the current sense amplifier and added with a slope compensation signal. Then, It controls the switches by comparing this signal with the COMP voltage. UV Comparator Oscillator Foldback Control 0.4V Internal Regulator 1.8V Shutdown Comparator Current Sense Amplifier BOOT VIN GND SW FB EN COMP VA VCC 6µA Slope Comp Current Comparator EA0.8V S R Q Q SS 1.2V Lockout Comparator VCC 130mΩ 150mΩ VARSENSE 5kΩ

Electrical Characteristics

(VIN = 12V, TA = 25 °C, unless otherwise specified) Absolute Maximum Ratings (Note 1) z Power Dissipation, PD @ TA = 25°C z Package Thermal Resistance (Note 2) z ESD Susceptibility (Note 3) Recommended Operating Conditions (Note 4) Parameter Symbol Test Conditions Min Typ Max Unit Shutdown Supply Current V EN = 0V -- 0.5 3 μA Supply Current V EN = 3V, VFB = 0.9V -- 0.8 1.2 mA Reference Voltage V REF 4.5V ≤ VIN ≤ 18V 0.788 0.8 0.812 V Error Amplifier Transconductance GEA ΔIC = ±10μA -- 940 -- μA/V High Side Switch On-Resistance RDS(ON)1 -- 150 -- m Ω Low Side Switch On-Resistance RDS(ON)2 -- 130 -- m Ω High Side Switch Leakage Current V EN = 0V, VSW = 0V -- 0 10 μA Upper Switch Current Limit Min. Duty Cycle, V BOOT − VSW = 4.8V -- 4 -- A COMP to Current Sense Transconductance GCS -- 3.7 -- A/V Oscillation Frequency f OSC1 -- 800 -- kHz Short Circuit Oscillation Frequency fOSC2 V FB = 0V -- 270 -- kHz Maximum Duty Cycle D MAX V FB = 0.7V -- 84 -- %

DS7237C-04 November 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Parameter Symbol Test Conditions Min Typ Max Unit Minimum On-Time t ON -- 100 -- ns Logic-High V IH 2 -- 18 EN Input Threshold Voltage Logic-Low V IL -- -- 0.4 V Input Under Voltage Lockout Threshold VUVLO V IN Rising 3.8 4.2 4.5 V Input Under Voltage Lockout Hysteresis ΔVUVLO -- 320 -- mV Soft-Start Current I SS V SS = 0V -- 6 -- μA Soft-Start Period t SS C SS = 0.1μF -- 13.5 -- ms Thermal Shutdown T SD -- 150 -- °C Note 1. Stresses beyond those listed “Absolute Maximum Ratings ” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability. Note 2. θ JA is measured at T A = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions.

DS7237C-04 November 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Typical Operating Characteristics Output Voltage vs. Output Current 3.22 3.24 3.26 3.28 3.30 3.32 3.34 3.36 3.38 00 . 511 . 52 Output Current (A) Output Voltage (V) VIN = 17V VIN = 12V VOUT = 3.3V Switching Frequency vs. Temperature 720 730 740 750 760 770 780 790 800 -50 -25 0 25 50 75 100 125 Temperature (°C) Switching Frequency (KHz) 1 VIN = 12V VIN = 17V VOUT = 3.3V, IOUT = 0.6A Switching Frequency vs. Input Voltage 740 750 760 770 780 790 800 810 820 4 6 8 1 01 21 41 61 8 Input Voltage (V) Switching Frequency (kHz) 1 VIN = 4.5V to 17V, VOUT = 3.3V, IOUT = 0.6A Reference Voltage vs. Temperature 0.780 0.785 0.790 0.795 0.800 0.805 0.810 0.815 0.820 - 5 0- 2 5 0 2 5 5 0 7 51 0 0 1 2 5 Temperature (°C) Reference Voltage (V) VIN = 12V, VOUT = 3.3V Reference Voltage vs. Input Voltage 0.780 0.785 0.790 0.795 0.800 0.805 0.810 0.815 0.820 4 6.6 9.2 11.8 14.4 17 Input Voltage (V) Reference Voltage (V) VIN = 4.5V to 17V Efficiency vs. Load Current 100 0.001 0.01 0.1 1 10 Output Current (A) Efficiency (%) VIN = 12V VIN = 17V VOUT = 3.3V

DS7237C-04 November 2012www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Time (500ns/Div) Output Ripple Voltage VOUT (5mV/Div) VSW (10V/Div) VIN = 12V, VOUT = 3.3V, IOUT = 2A IL (1A/Div) Time (500ns/Div) Output Ripple Voltage VOUT (5mV/Div) VSW (10V/Div) VIN = 12V, VOUT = 3.3V, IOUT = 1A IL (1A/Div) Time (100 μs/Div) Load Transient Response VOUT (200mV/Div) IOUT (1A/Div) VIN = 12V, VOUT = 3.3V, IOUT = 0A to 2A Time (100 μs/Div) Load Transient Response VOUT (200mV/Div) IOUT (1A/Div) VIN = 12V, VOUT = 3.3V, IOUT = 1A to 2A Output Current Limit vs. Temperature 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 - 5 0- 2 5 0 2 5 5 0 7 51 0 0 1 2 5 Temperature (°C) Output Current Limit (A) VIN = 12V, VOUT = 3.3V Output Current Limit vs. Input Voltage 4 6 8 1 01 21 41 61 8 Input Voltage (V) Output Current Limit (A) VIN = 4.5V to 17V, V OUT = 3.3V

DS7237C-04 November 2012 www.richtek.com ©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Time (10ms/Div) Power Off from EN VIN = 12V, VOUT = 3.3V, IOUT = 2A VOUT (2V/Div) VEN (5V/Div) IOUT (2A/Div) Time (10ms/Div) Power On from VIN VIN = 12V, VOUT = 3.3V, IOUT = 2A VOUT (2V/Div) VIN (5V/Div) IOUT (2A/Div) Time (25ms/Div) Power Off from VIN VIN = 12V, VOUT = 3.3V, IOUT = 2A VOUT (2V/Div) VIN (5V/Div) IOUT (2A/Div) Time (10ms/Div) Power On from EN VIN = 12V, VOUT = 3.3V, IOUT = 2A VOUT (2V/Div) VEN (5V/Div) IOUT (2A/Div)

Application Information

The resistive divider allows the FB pin to sense the output voltage as shown in Figure 1. Figure 1. Output Voltage Setting Where VREF is the reference voltage (0.8V typ.). driver voltage for the high side MOSFET. Figure 2. External Bootstrap Diode and CEN capacitor from the VIN pin (see Figure 3).

0.8 CSoft-Start time t = , if C capacitor I

Figure 3. Enable Timing Control Figure 4. Digital Enable Control Circuit

©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. is disabled during soft-start period. large inductor to achieve this goal. Table 2. Suggested Inductors for Typical see Table 2 for the inductor selection reference. Figure 5. Hiccup Mode Under Voltage Protection approximately 20°C, the converter will resume operation. temperature should be lower than 125°C. and decreases with higher inductance. trapezoidal current at the source of the high side MOSFET.

©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Figure 7. Derating Curve of Maximum Power Dissipation IN large enough to damage the part. and temperature difference between junction to ambient. the junction to ambient thermal resistance. as described in a later section. thermal performance by the PCB layout copper design.

©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Figure 6. Thermal Resistance vs. Copper Area Layout \` Connect feedback network behind the output capacitors. components near the RT7237C.

©Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Figure 8. PCB Layout Guide Table 3. Suggested Capacitors for CIN and COUT

DS7237C-04 November 2012 www.richtek.com Richtek Technology Corporation 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnish ed by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringeme nts of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of R ichtek or its subsidiaries. Outline Dimension A BJ F H M C D I Y X EXPOSED THERMAL PAD (Bottom of Package) 8-Lead SOP (Exposed Pad) Plastic Package Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 4.801 5.004 0.189 0.197 B 3.810 4.000 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.510 0.013 0.020 F 1.194 1.346 0.047 0.053 H 0.170 0.254 0.007 0.010 I 0.000 0.152 0.000 0.006 J 5.791 6.200 0.228 0.244 M 0.406 1.270 0.016 0.050 X 2.000 2.300 0.079 0.091 Option 1 Y 2.000 2.300 0.079 0.091 X 2.100 2.500 0.083 0.098 Option 2 Y 3.000 3.500 0.118 0.138

Product Information

SLF12565 specifications and overview.

Summary

RT7237C

Description

RT7237C

Source title SLF12565 Datasheet(PDF) - Richtek Technology Corporation

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