Texas Instruments TPS60230EVM-047 - Manual (Page 9)

Input/Output Connector Descriptions
3
TPS60230EVM-047
2.2 Setup
Connect an input supply or battery between J1 and J2. The voltage range on
this supply should stay between 2.7V and 6.0V. Set the appropriate brightness
by configuring JP1 and JP2.
2.3 Operation
The EVM has been optimized to operate from a single-cell Li-Ion battery with
an input voltage range of 2.7V to 6.0V. The value for R1 programs the maxi-
mum LED current. For this EVM, the maximum current is set to 20mA. Howev-
er, by changing the value of R1, LED currents up to 25mA can be achieved.
Currents less than 20mA can be achieved by appropriately configuring JP1
and JP2, as shown in Table 1.
Table 1. Relative LED Current Levels
JP1 (EN2) JP2 (EN1) LED CURRENT
0 0 0
0 1 1/3 full
1 0 2/3 full
1 1 Full (20mA for R1 = 7.87k Ω )
EN1 and EN2 can also be used for pulse width modulator (PWM) dimming.
The PWM signal can be applied to EN1, EN2, or both. In this case, the LED
current is proportional to duty factor and can have a maximum current dictated
by how EN1 and EN2 are configured. The maximum recommended PWM fre-
quency is 50kHz, and the minimum recommended ON time is 2.5us. Refer to
the datasheet (SLVS516) for more information in regards to PWM dimming.
2.4 Test Results
The efficiency curve in Figure 1 reflects the power delivered to the LED. The
output power used for the efficiency calculation is the sum of all the LED cur-
rents multiplied by the LED forward voltage.
Figure 1. Efficiency vs VIN
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 5.9 6.3 6.5
E
ff
ici
en
cy
(%
)
Input Voltage (V)
EN2 and EN1 = On
I
LED
= 20mA
90
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10
0