LM3528TMEV National Semiconductor, LM3528TMEV Datasheet - Page 5

• Manufacturer Part Number: LM3528TMEV
• Description: BOARD EVAL FOR LM3528 12MCRSMD
• Manufacturer: National Semiconductor

Specifications of LM3528TMEV

• Current - Output / Channel: 20mA
• Outputs And Type: 2, Non-Isolated
• Voltage - Output: 21V
• Features: Dimmable, I²C Interface
• Voltage - Input: 2.5 ~ 5.5V
• Utilized Ic / Part: LM3528
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Board Operation
To operate the LM3528 Evaluation Board, connect a 2.5V to
5.5V supply between the IN header and GND and attach an
I
TERNAL CONTROL INTERFACE section of this document.
External Control Interface
There are two methods for controlling the LM3528 Evaluation
Board. The first option is via a National Semiconductor USB
Interface Board. The second option is by using the SDA and
SCL headers available on the upper left corner of the board.
When option 1 is used, the USBL and USBR connectors plug
directly into a National Semiconductor USB Interface Board.
The connectors are keyed so they will only fit one way. On the
LM3528 Evaluation Board the VIN/VUSB jumper allows for
power to come from IN or from the USB . The USB Board can
supply 3.3V from an on board regulator or 5V directly from the
PC (see documentation for the National Semiconductor USB
interface board). When power from the USB is desired con-
nect a jumper across VIN/VUSB, if power is supplied from the
IN header leave VIN/VUSB open. DO NOT jumper VIN/VUSB
while an external source is connected to IN as this will make
a conflict between the USB Board and the external power
supply.
The USB interface board interfaces directly with the
LM3528.exe graphical interface via the PC (see LM3528 I
Compatible Interface Program section). If the LM3528.exe
program is not used then control of the LM3528 Evaluation
Board can be done by connecting an external I
interface directly to the SCL and SDA headers. Both the SDA
and SCL lines have 10 kΩ pull-ups installed on the board.
Basic Connections (Refer to Figure
1)
The LM3528 Evaluation Board is configured for two strings of
six LEDs. There are two resistor pads on the bottom side of
the board (R1, and R2) which serve as feedback resistors for
operation of the LM3528 in voltage output mode (OLED
mode). When operating in OLED mode (with D1S – D6S in-
stalled) the OLED/LED jumper must be installed in order to
connect the center tap of the resistive divider (R1, and R2) to
the SUB/FB pin. Additionally, (in OLED mode) the SOPEN
header should be removed otherwise the secondary LED
string will interfere with the feedback divider and cause erratic
operation.
2
C interface using one of the methods described in the EX-
2
C compatible
2
C
5
JUMPER CONNECTIONS/COMPONENT DESCRIPTIONS:
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J1 is a 3-pin, 3-position jumper. The left most pin (pin 1 in
figure 1) connects to the 3.3V supply from the USB board
(pin 14 on the USBL connector). The right most pin (pin 3
in Figure 1) connects to IN. The top middle pin (pin 2 in
Figure 1) connects to VIO of the LM3528, the top side of
the pull-up resistors (RSDA, RSCL, RGPIO, RGPIO1),
and the anode of the indicator diode D2.
The SOPEN and MOPEN jumpers allow for the
disconnection of the LEDs from the LM3528’s output.
SOPEN opens the SECONDARY (SUB/FB) LED string
while MOPEN opens the MAIN LED string. This is useful
in testing OVP or disabling a string if OLED mode is
required.
The 5-pin, 5-position jumpers (2/3/4/5/6 LEDM and
2/3/4/5/6 LEDS) located above the MAIN and
SECONDARY LED strings respectively, allow for shorting
out of different LEDs in both the MAIN and the
SECONDARY strings. Both jumpers have their center pin
(pin 5 in Figure 1) connected to the cathode of the sixth
LED in each string. Referring to jumper 2/3/4/5/6 LEDs,
connecting pin 4 to pin 5 will short D6S, thus making the
SECONDARY string a five-LED configuration. Connect
pin 3 to pin 5 to short D5S and D6S resulting in a four-LED
configuration. Connect pin 2 to pin 5 for a three-LED
configuration (D4S – D6S shorted). Connect pin 1 to pin 5
for a two-LED configuration (D3S – D6S shorted), and
leave jumper 2/3/4/5/6 LEDS open for a six-LED
configuration. The operation for jumper 2/3/4/5/6 LEDM is
the same only it applies to the MAIN LED string.
Resistors R4 and R5 have 0Ω’s across them. The 0Ω
resistors can be replaced with current sense resistors for
measuring LED current. Two vias have been placed at the
terminals of each resistor which fit standard 0.1” headers.
The OLED/LED jumper connects or disconnects the
resistive divider from the SUB/FB node. In white LED
mode the jumper should be open. In OLED mode the
jumper should be shorted so the SUB/FB node can
regulate VOUT at a constant voltage.
D2 is a RED indicator diode that flashes the programmed
pattern programmed into the PGEN registers (see
LM3528 datasheet). R3 is a 205Ω current limiting resistor
for D2. RGPIO is a 1MΩ pull-up resistor for the HWEN/
PGEN/GPIO output. On power up, the HWEN/PGEN/
GPIO output defaults as an active high hardware enable
(HWEN). RGPIO is installed to ensure that HWEN/PGEN/
GPIO pulls high on start-up.
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