SEL1

JU4 SHUNT POSITION

REG (V)

BATT

1-2

1.8

GND

2-3

2.3

Unconnected

Not installed*

3.3

_________________________________________________________________ Maxim Integrated Products 4

MAX17710 Evaluation Kit

Evaluates: MAX17710

Charger

The CHG test point monitors the CHG pin. The CHG test

point is connected to the output of the boost regulator

and the CHG pin is the input to the battery charger. The

IC charges the MEC based off the voltage on the CHG

test point. The power sources to the CHG test point can

come from solenoid, piezo, mechanical, or RF sources,

and must exceed the MEC voltage. When CHG exceeds

the MEC voltage by 50mV, the IC uses the CHG supply

to charge the on-board MEC. The IC is designed to use

input supplies from energy-harvesting sources, which

are highly variable, poorly regulated, and usually power-

limited. Apply the variable input supply source to the

AC+ and AC- test points. The power source is rectified

and supplied to the CHG test point through the full-wave

bridge diode (D2).

Internal Boost

For power sources that are lower than the battery

voltage, such as solar or the above-mentioned sources,

the IC features a boost converter to step up the voltage to

charge the on-board MEC. The output of the boost is the

CHG test point. The IC uses the voltage on the CHG test

point to charge the MEC. An additional power source can

be present on CHG through the AC+ and AC- test points

while the boost is active.

Figure 1 shows the CHG test-point voltage observed on an

oscilloscope with ambient light using the on-board

solar cells as the power source. The number of pulses

increase as the EV kit is brought closer to the light source

and decrease when taken away from the light source.

Power Sources

The on-board power source is a parallel connection of

three solar cells. The voltage can be monitored on the

SOLAR+ and GND test points. The start-up voltage for

the IC boost is approximately 750mV at the FB pin. To

supply an external power source, remove the shunt from

jumper JU3 and apply the power source to the SOLAR+

and GND test points.

On-Board Micro-Energy Cell (BATT)

The EV kit features the THINERGY micro-energy cell

(MEC) from IPS as the on-board energy storage cell.

The MEC101 included on the EV kit is roughly the size of

a postage stamp and is soldered directly to the board.

The BATT footprint can also accommodate the MEC201.

Caution: The MEC case is conductive. To protect the

MEC, do not touch the MEC with conductive material.

MEC Pack Power

The IC has a regulator output and battery pack output

(PCKP) to provide power to external loads. The IC PCKP

test point provides the MEC voltage to external loads

while the REG test point provides a regulated voltage

(Table 3). External unregulated loads from the MEC

should always be connected through the PCKP test

point. External loads connected directly from the MEC

can cause irreversible damage to the MEC if the voltage

goes too low.

LED Indicator On Pack Power

The D5 LED is connected through a digital FET at the

PCKP test point. The LED blinks as pulses are generated

at the CHG test point. The LED is a visual display that the

boost regulator is operating.

Logic Inputs

The EV kit provides various pushbutton switches and test

points to evaluate the device. There are two regulators

internal to the IC, which are available through AE and

LCE. AE controls the default regulator and LCE controls

the low-current regulator.

Regulator Output Enable (AE)

The IC features a default regulator that can be enabled

by the AE signal. Press the S1 switch to connect PCKP

and enable the default regulator. Press the S2 switch

to disconnect PCKP and disable the default regulator

output. The output voltage is selected by jumper JU4

(see Table 3). If the MEC voltage drops below 2.15V,

the AE and PCKP outputs are disabled until a charger

is applied.

Low-Current Mode Enable (LCE)

The IC features a low-current regulator that reduces

the quiescent current by a factor of 5. The low-current

regulator can be enabled by the LCE and AE signals.

To enter the low-current mode, first turn on the default

regulator by pressing S1, then press S3 to enable the

low-current regulator, and finally turn off the default regu-

lator by pressing S2. Afterwards, press S4 to disable the

low-current regulator. If low-current mode is enabled,

pressing S1 enables the default regulator, but pressing

S2 switches back to the low-current regulator if originally

enabled. If the MEC voltage drops below 3V, the AE and

PCKP outputs are disabled until a charger is applied.

Regulator Output Voltage (SEL1)

Table 3 shows the regulator output options. SEL1 is con-

nected to jumper JU4. The regulator output is locked

when the regulator is active. To change the regulator

output voltage, first change the setting on jumper JU4 to

obtain the desired output voltage (Table 3), then press

S2 and S4 to disable both the default and low-current

regulators. Lastly, press S1 to enable the default regula-

tor and optionally S3 to enable the low-current regulator.

The regulator output voltage can be monitored on the

REG test point and outputs the new voltage.

Table 3. Regulator Output Voltage (SEL1)

*Default position.