Evaluates: MAX1722/MAX1723/MAX1724
MAX1724 Evaluation Kit
2 _______________________________________________________________________________________
3.6V Output (right side):
1) Connect a 0.91V to 3.6V supply to the VBATT pad.
Connect the supply ground to the GND pad.
2) Connect a voltmeter to the VOUT pad.
3) Verify there is a shunt across pins 1 and 2 of
jumper JU2 to connect BATT to VBATT for the
MAX1722.
4) Turn on the power supply and verify that the output
is at 3.6V.
For instructions on selecting feedback resistors for
other output voltages, see Evaluating Other Output
Voltages (Right Side).
Detailed Description
The MAX1724 EV kit contains two separate boost
switching-regulator circuits. The left-side circuit
(MAX1724) supplies a preset 3.3V output. The right-
side circuit (MAX1722) supplies an adjustable 3.6V out-
put, but can also be set from 2.0V to 5.5V. Both circuits
regulate with input voltages from 0.91V to VOUT, but
can accept higher input voltages (below 5.5V) if it is
acceptable for the output voltage to rise above the set
VOUT. Output current for both circuits is 50mA with a
1.2V input, and 100mA for a 2.4V input.
The 3.6V output voltage (right side) can also be adjust-
ed from 2.0V to 5.5V using external resistors R1 and
R2. The input voltage ranges from 0.91V to (VOUT)
when operating from a DC source.
The MAX1724 boost converter (left side) features a
0.1µA shutdown mode.
Jumper Selection
MAX1724 Circuit (Left Side)
The MAX1724 EV kit’s shutdown mode reduces the IC’s
quiescent current to 0.1µA (typ), preserving battery life.
Jumper JU1 selects the shutdown mode for the
MAX1724. Table 1 lists the MAX1724 jumper options.
MAX1722 Circuit (Right Side)
When jumper JU2 on the right-side circuit is used with a
MAX1722, pins 1 and 2 must be connected together so
that BATT is connected to the battery input (VBATT).
When the right-side circuit is used to evaluate a
MAX1723, see Evaluating the MAX1723 section. Table
2 lists the MAX1722 jumper options.
3.6V Output (right side):
1) Connect a 0.91V to 3.6V supply to the VBATT pad.
Connect the supply ground to the GND pad.
2) Connect a voltmeter to the VOUT pad.
3) Verify there is a shunt across pins 1 and 2 of
jumper JU2 to connect BATT to VBATT for the
MAX1722.
4) Turn on the power supply and verify that the output
is at 3.6V.
For instructions on selecting feedback resistors for
other output voltages, see Evaluating Other Output
Voltages (Right Side).
Evaluating Other Output Voltages
(Right Side)
The MAX1722 output is set to 3.6V by feedback resis-
tors R1 and R2. To generate output voltages other than
3.6V (2.0V to 5.5V), select different external voltage-
divider resistors (R1, R2). Refer to the Setting the
Output Voltage section in the MAX1722/MAX1723/
MAX1724 data sheet for instructions on selecting R1
and R2 for the MAX1722/MAX1723.
Evaluating the MAX1723
The MAX1723 can be evaluated using the MAX1722
circuit (right side). Replace the MAX1722 with a
MAX1723EZK. Diode D1 (Motorola MBR0520L or equiv-
alent) may be necessary for low-voltage startup. Refer
to the Low-Voltage Startup Oscillator section in the
MAX1722/MAX1723/MAX1724 data sheet for additional
instructions on selecting D1.
SHDN PIN MAX1724 OUTPUT
1-2 Connected to
VBATT
MAX1724 enabled,
VOUT = 3.3V
2-3 Connected to GND Shutdown mode,
VOUT = VBATT - VDIODE
SHUNT
LOCATION
Table 1. MAX1724 Jumper JU1 Functions