SP6122EB Datasheet, PDF (3/6 Pages) Sipex Corporation – Evaluation Board Manual

SP612 Evaluation Board Divider Resistors: The values of R1 and R2 are selected
to program 1.9V output, with 1.5V trim voltage Vb, and R1 = 500ohm:
i3 = (Vout-Vb)/R1=(1.9-1.5)/500 = 800uA.
The external voltage divider will add only 800uA to the load. Divider Resistor R2 is:
R2 = Vb/(i3-i1)=1.5/(800uA-20uA) = 1.9K
The user of the SP6122 Evaluation Board can use the above equations for i3 and R2 to
modify R2 and change the output voltage to be any voltage from Vb (1.5V) to as high as
the input voltage. And if you want the output voltage to be the preset voltage Vb (1.5V),
just short a wire across R1.
Vout
R1
i3
500
SP6122
Vb ^Pin3
R2
i2
1.9K
Rin1
Va
-
i1 Rin2
62.5K
+
Error
Amplifier
+
-
1.25
Figure 1. Schematic: Output Voltage Divider Resistors
POWER SUPPLY DATA
The SP6122 is engineered for size and minimum pin count, yet has a very accurate
1.5% reference over line, load and temperature. Figure 2 data shows a typical SP6122
Evaluation Board Efficiency plot, with efficiencies to 88% and output currents to 4A.
Load Regulation plot in Figure 3 shows an essentially flat response of only 3mV change
for up to 4A load. Figure 4 Line Regulation illustrates a 1.90V output that varies only
4mV or 0.2% for an input voltage change from 3.3V to 5.5V. While data on individual
power supply boards may vary, the capability of the SP6122 of achieving high accuracy
over load and line shown here is quite impressive and desirable for accurate power
supply design.
Rev. 5/23/01
SP6122 Evaluation Board Manual
3
© Copyright 2001 Sipex Corporation