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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.
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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.
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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
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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
[email protected]
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
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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
[email protected]
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
[email protected]
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
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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
[email protected]
5V
D8
[email protected]
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
[email protected]
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
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AN347
Pericom Semiconductor Corp.
www.pericom.com
7/4/2013