347 PI5USB266 Car Charger design with PI5USB266 by Noyes Mok Table of Contents 1. Introduction .................................................................................................................................. 1 2. Overview ....................................................................................................................................... 2 2.1 PI5USB266 .........................................................................................................................3 2.2 Input Protection ................................................................................................................4 2.3 DC-DC convertor ...............................................................................................................5 2.4 Output Protection .............................................................................................................5 3. Typical Application Schematic.................................................................................................... 6 4. References .................................................................................................................................... 6 1. Introduction Pericom’s PI5USB266 is USB charge controller IC which suitable for the dual USB port charger design in different application, for example automotive and home appliance. PI5USB266 supports most of the charging protocols for the portable device and the USB device can be drawn the current efficiently to charge itself. This application note describes how to use PI5USB266 to design a dual USB port charger for automotive application (USB car charger). This design is fulfill the Battery charger specification BC1.1 / BC1.2 and YD/T-1591 Chinese Telecom Standard. It also supports the non-standard protocol such as Apple 2.1A charging mode. Page 1 of 6 AN347 Pericom Semiconductor Corp. www.pericom.com 7/4/2013 347 2. Overview Input = +24V OR Output = +5V / 2.1A for each USB port Input = 12V Figure 1, Block diagram for car charger application Input voltage The typical output voltage of the cigarette lighter socket is 12V (car) or 24V (truck), therefore the input voltage supply for the car charger should be support up to at least 36V. Output voltage According to the USB organization, the VBUS output voltage of USB port should be 5V (nominal) with tolerance of ±5% (4.75V to 5.25V), therefore, the output voltage of the car charger should be followed this requirement. Output current PI5USB266 can support Apple 2.1A charging mode, therefore the maximum output current for each port on car charger should support 2.1A which means the total current should be about 4.2A. Page 2 of 6 AN347 Pericom Semiconductor Corp. www.pericom.com 7/4/2013 347 Output protection +5V D1± Input protection 12V / 24V input DC-DC convertor +5V (12V/24V to 5V) USB port 1 (5V / 2.1A) PI5USB266 D2± Output protection USB port 2 (5V / 2.1A) +5V Figure 2, Block diagram of the PI5USB266 dual USB port car charger The car charger should be divided to few parts: a) PI5USB266 – charging mode detection b) Input Protection: Over voltage Protection c) DC- DC convertor d) Output Protection: over current protection / Thermal protection / UVLO 2.1 PI5USB266 – charging mode detection PI5USB266 is an intelligent charging IC which is detecting the USB data line voltage of the mobile device and providing the suitable charging mode to let the mobile charge in efficient way. PI5USB266 requires +5V±10% input supply voltage on Vdd pin (Pin 12 & Pin 16) and 0.1uF or greater value decoupling capacitor should be mounted as close to each Vdd pin. D1+ (Pin 3), D1- (Pin 4) and D2+ (Pin 7), D2- (Pin 8) are connected to the D+ and D- pins of the USB receptacle connectors. The D1± and D2± are performed as Apple 2.1A charger after power up. Once the mobile device plug into the USB port, PI5USB266 will check the D± voltage then identifies the attached mobile device type and provides the correct charging mode. When the mobile device recognized the correct charging mode from D± pin of the USB port, mobile device will draw the current that it required. D1± & D2± can do the mode detection separately. S1 (Pin 5) and S2 (Pin 9) are the control pin of PI5USB266 and both pins should tie to ground for normal operation. For details, please refer to below schematic for PI5USB266 session Page 3 of 6 AN347 Pericom Semiconductor Corp. www.pericom.com 7/4/2013 347 C2 22uF J1 1 2 3 4 VBUS DD+ GND USB2.0 Type A Receptacle connector 5 9 8 7 6 5 4 3 2 S2 D2D2+ NC S1 D1D1+ NC ShellShell 10 OUT2 C7 0.1uF C8 22uF J2 VBUS DD+ GND USB2.0 Type A Receptacle connector 5 1 2 3 4 6 U1 ShellShell HGND GND 1 20 C1 0.1uF GND 11 VDD NC GND NC VDD NC GND NC NC 0.1u 12 13 14 15 C4 16 17 0.1u 18 19 21 C3 NC VOUT_5V 6 OUT1 PI5USB266ZHE@TQFN20 Figure 3, Schematic of PI5USB266 with USB connectors 2.2 Input Protection The instant pulse / surges voltage level may burn the car charger. The lowest cost solution is adding a 5A fuse implemented between the input of the DC-DC convertor and the output signal of the cigarette lighter socket as protection. An additional protection way is adding the unidirectional transient-voltage-suppression (TVS) diode. TVS diode presents high impedance to the protected circuit. The TVS diode junction avalanches providing a low impedance path for the transient current when the voltage is exceeded the normal operating voltage. Figure 4, TVS connection diagram Page 4 of 6 AN347 Pericom Semiconductor Corp. www.pericom.com 7/4/2013 347 2.3 DC-DC convertor PI5USB266 can let the portable device charge up to 2.1A for each USB port. In this dual USB car charger mode design, the DC-DC convertor need to convert the output voltage of the car / truck cigarette socket 12V / 24V to 5V (4.75V to 5.25V) with output current >= 4.2A high current output DC-DC convertors can be found from Linear Technology and AXElite Technology Co. Ltd. 2.4 Output Protection If the DC-DC convertor part didn’t have the under-voltage lockout (UVLO), short circuit protection and thermal protection, external output protection circuit on VBUS pin is required. This circuit is not only protecting the car charger itself but also protecting the mobile device not to be burned. One of the suggestions is using the Vbus power switch at Vbus pin for each USB port. Pericom’s PI5PD2068 (EN pin = active Low) and PI5PD2069 (EN pin = active high) are the power switch which limited the current draw up to 2.85A (typ.). Once the short-circuit situation is presented, PI5PD2068 / PI5PD2069 will limit the output current by switching into a constant-current mode and enable the over-current pin (OC# pin). The heavy overloads / short-circuits will increase the power dissipation in the switch which causing the junction temperature rising (> 135oC), then the thermal protection circuit in PI5PD2068/PI5PD2069 will turn off the switch to prevent damage. PI5PD2068 / PI5PD2069 will remain off until the junction temperature cools down to approximate 125oC and the switch will recover automatically. VOUT_5V U3 1 2 3 4 R6 37k GND IN IN EN PAD_GND OUT OUT OUT OC# 9 8 7 6 5 OUT1 VOUT_5V D6 PI5PD2069@SOIC8 2 1 R8 560 LED_R Assert during over Temperature, Low OUT or Reverse voltage conditions C2 22uF J1 1 2 3 4 PAD_GND OUT OUT OUT OC# 9 8 7 6 5 OUT2 OUT2 VOUT_5V D7 PI5PD2069@SOIC8 2 C7 0.1uF C8 22uF J2 1 1 2 3 4 R17 560 LED_R Assert during over Temperature, Low OUT or Reverse voltage conditions VBUS DD+ GND 6 GND IN IN EN ShellShell R16 37k 5 U4 1 2 3 4 USB2.0 Type A Receptacle connector USB2.0 Type A Receptacle connector 5 VOUT_5V VBUS DD+ GND ShellShell C1 0.1uF 6 OUT1 Figure 5, Schematic of Power switch (PI5PD2069) with USB connectors Page 5 of 6 AN347 Pericom Semiconductor Corp. www.pericom.com 7/4/2013 347 3. Typical Schematic for Dual USB port car charger 5V U6 1 2 3 4 GND IN IN EN R20 37k 9 8 7 6 5 PAD_GND OUT OUT OUT OC# OUT1 2 20 J3 9 8 7 6 5 4 3 2 1 2 3 4 VBUS DD+ GND USB Port 2 5 S2 D2D2+ NC S1 D1D1+ NC R21 560 6 C13 22uF ShellShell C14 0.1uF GND GND VDD NC GND NC VDD NC GND NC NC 0.1u 12 13 14 15 C12 16 17 0.1u 18 19 1 C17 D10 DIODE TAZ 10 11 NC 5V HGND FUSEHOLDER DC (6 - 36V) to DC (5V) Converter 21 F1 Car Cigrarette Lighter Socket Output 1 LED_R OUT1 PI5USB266ZHE@TQFN20 5V D8 PI5PD2069@SOIC8 U7 5V U8 1 2 3 4 GND IN IN EN R22 37k PAD_GND OUT OUT OUT OC# 9 8 7 6 5 OUT2 5V D9 PI5PD2069@SOIC8 2 1 OUT2 R23 560 J4 VBUS DD+ GND USB Port 1 5 1 2 3 4 ShellShell C15 22uF 6 LED_R C16 0.1uF Figure 6, Application Diagram of PI5USB266 Dual USB port Car charger 4. References 1) Battery Charging Specification Revision 1.2 (December 7, 2010) 2) YD/T 1591-2009 Technical Requirements and test method for power adapter and charging /data of mobile telecommunication terminal Equipment 3) Pericom PI5PD2068 / 2069 datasheet Page 6 of 6 AN347 Pericom Semiconductor Corp. www.pericom.com 7/4/2013