_________________________________________________________________ Maxim Integrated Products 2
MAX44264 Evaluation Kit
Evaluates: MAX44264
Quick Start
Required Equipment
• MAX44264 EV kit
• 1.8V to 5.5V, 100mA DC power supply
• Voltmeter
Procedure
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation. Caution: Do not turn on
the power supply until all connections are completed.
1) To configure the EV kit as an op-amp buffer to
balance super capacitors C1 and C2 charge, set
jumpers JU1, JU2, and JU3 in their default positions,
as shown in Table 1.
2) Set the power supply to provide 5V and then disable
the power supply.
3) Connect the power-supply positive terminal to the
VDD PCB pad.
4) Connect the power-supply ground to the GND PCB
pad (nearest the VDD PCB pad).
5) Enable the power supply.
6) Verify that the OUT PCB pad is at 2.5V.
Detailed Description of Hardware
The MAX44264 EV kit contains the MAX44264 IC, which
is a rail-to-rail micropower op amp with an ultra-low
750nA supply current designed in a 6-bump WLP. The
EV kit operates from a single 1.8V to 5.5V DC power
supply.
Default Application Circuit
The EV kit comes preconfigured as a buffer used in a
super-capacitor charge-balancing circuit. Super capaci-
tors offer exceptional charge storage density and are
widely used to prolong the life of weak batteries sub-
ject to high current-load pulses, or to buffer a weak
energy source to a high-power load in energy-harvesting
devices. In such applications, it is common to have a
stack of super capacitors connected in series to achieve
the desired working voltage. The EV kit demonstrates
an active, super-capacitor charge-balancing circuit that
distributes the charge equally across two series-connected
super capacitors (C1 and C2), ensuring identical voltage
across each capacitor. This circuit prevents overvoltage
conditions from occurring across either of the super
capacitors due to a difference in leakage currents and
tolerance in the capacitor values. The IC’s ultra-low power
consumption of 750nA and CMOS inputs allow a power-
efficient solution to the super-capacitor charge-balancing
problem.
Op-Amp Configurations
While super-capacitor charge balancing is the featured
application, the EV kit also provides flexibility to easily
reconfigure the op amp into any of the four common
circuit topologies: inverting amplifier, noninverting ampli-
fier, differential amplifier, or buffer. Table 2 lists the JU1,
JU2, and JU3 jumper settings for the various op-amp
configurations. The configurations are described in the
next few sections.
Important Note: Remove super capacitors C1 and
C2 when not demonstrating super-capacitor charge
balancing in the four configurations detailed in the
Noninverting Amplifier, Inverting Amplifier, Differential
Amplifier, and Buffer Amplifier sections.
Table 2. JU1, JU2, JU3 Jumper Functions
(IN-, IN+, REF)
Table 1. Default Shunt Positions
JUMPER SHUNT
POSITION DESCRIPTION
JU1 Not installed IN- = OUT (through resistor R2)
JU2 2-3 IN+ = VDD/2
JU3 Installed
OP-AMP
CONFIGURATION
SHUNT POSITION
JU1 JU2 JU3
Inverting Installed
1-2 Not
installed
Differential
Noninverting Not
installed
Buffer
Super-capacitor
buffer
Not
installed 2-3 Installed