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December 2009 Rev. 1.0.0
Exar Corporation www.exar.com
48720 Kato Road, Fremont CA 94538, USA Tel. +1 510 668-7000 – Fax. +1 510 668-7001
GENERAL DESCRIPTION
The XRP6840 is a controlled-current dual-cell
supercapacitor charger and high power LED
driver. Operating from a standard lithium-ion
battery, the XRP6840 provides up to 4.3A of
programmable Flash LED current and up to
600mA and 5.6V of programmable
supercapacitor charging current and voltage.
The XRP6840EVB, Exar’s XRP6840 Evaluation
Board, supports either XRP6840A or
XRP6840B in a 4x4 TQFN package and is fitted
by default with the XRP6840A supporting three
channels.
With 1x, 1.5x and 2x charge pump operating
modes, XRP6840EVB can provide a stable
drive current for up to 3 1.5A, 4W Luxeon
Flash LEDs. The evaluation board is a
completely assembled and tested surface
mount board which provides easy probe
access points to all XRP6840 inputs and
outputs for easy connection and measuring.
The Evaluation Board schematic diagram is
shown in Figure 1.
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V
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FEATURES
• Programmable 4.3A Flash LED Driver
− Torch and Flash Modes
• Programmable Supercapacitor Charger
− 600mA Adjustable Charging Current
− Programmable Supercapacitor Voltage
− Active Voltage Balance Control
• Tri-mode Charge Pump Architecture
− 1x, 1.5x, 2x Operation Modes
− 2.4MHz Switching Frequency
• I
2
C Serial Interface
EVALUATION BOARD SCHEMATICS
Fig. 1: XRP6840 Evaluation Board Schematics
J4_LED3
J4_LED2
J4_LED1
R8
1M
R6
10K
CIN
22uF
R3
0.1
R2
0.1
R1
0.1
D2
LED
D3
LED
J7
R7
N P
COUT
10uF
C2
0.47uF
C3
CAPxx
R5
NP
D1
LED
R4
NP
VIN: 2.7-5.5V
U1
CGND
1
RDY
2
LED2
8
LED1
7
SDA
4
SCL
3
LED3
9
RESET_N
6
NC
12
GND
13
CAP
14
VOUT
15
C2P
16
C2N
17
C1P
18
C1N
19
PGND
11
FLASH
10
PGND
5
VIN
20
FLASH
C1
0.47uF
SW1
SW PUSHBUTTON
D4
Flash Ready Indicator
U1
R9
3k
FLASH
Vin
Vin
RDY
VOUT
RDY
RDY
Vin
XRP6840
FLASH
J1
J6
1
2
3
4
J5
1
2
3
J2J3
