MAX8728EVKIT Maxim Integrated Products, MAX8728EVKIT Datasheet - Page 3

• Manufacturer Part Number: MAX8728EVKIT
• Description: Display Modules & Development Tools MAX8728 KIT MAX8728 KIT
• Manufacturer: Maxim Integrated Products

Specifications of MAX8728EVKIT

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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The MAX8728 EV kit is fully assembled and tested.
Follow these steps to verify board operation. Do not
turn on the power supply until all connections are
completed:
1) Verify that a shunt is installed across jumper JU1
2) Verify that a shunt is installed across pins 1 and 2 of
3) Verify that no shunt is installed across jumper JU3
4) Verify that a shunt is installed across pins 1 and 2 of
5) Verify that a shunt is installed across pins 1 and 2 of
6) Preset the power supply to +12V and disable the
7) Connect the positive terminal of the power supply to
8) Turn on the power supply.
9) Verify that the step-down switching regulator output
10) Verify that the step-up switching regulator output
11) Verify that the gate-on supply (VSRC) is +28V.
12) Verify that the gate-off supply (VGOFF) is -6V.
The MAX8728 EV kit contains a step-down switching
regulator, a step-up switching regulator, a positive two-
stage charge pump, a negative single-stage charge
pump, and a high-voltage switch matrix. The MAX8728
switching frequency is configured for 1.5MHz. The EV
kit is configured to operate from a +10VDC to
+13.2VDC power supply that can provide at least 2A.
Operation below +10V (down to +7V) is possible, but
requires changes in component values, charge-pump
configurations, output voltages and currents, or other
parameters. Refer to the MAX8728 IC data sheet for
additional information.
+10V to +13.2V, 2A DC power supply
One voltmeter
(EV kit ON).
jumper JU2 (enables step-up, charge pumps, and
switch-control block).
(no capacitive dummy load C23).
jumper JU4 (VGON discharges toward AVDD).
jumper JU5 (high-voltage, switch-control block set
to mode 1).
output.
the VIN pad on the EV kit. Connect the negative ter-
minal of the power supply to the PGND pad next to
the VIN pad.
(OUT1) is +3.3V.
(AVDD) is +13.5V.
_______________________________________________________________________________________
Recommended Equipment
Detailed Description
Quick Start
MAX8728 Evaluation Kit
The EV kit is configured for a 1.5MHz switching frequency.
Operation at 500kHz or 1MHz is possible, but requires
component changes. See the Switching Frequency
Selection (FSEL) section.
As configured, the step-down switching regulator
(OUT1) generates a +3.3V output and can provide at
least 2A. The step-down switching-regulator output
voltage can be adjusted from 2V to 3.6V by replacing
feedback resistors R1 and R2. Refer to the Detailed
Description, Step-Down Regulator section in the
MAX8728 data sheet.
The step-up switching regulator (AVDD) generates a
+13.5V output and can provide at least 500mA. The
step-up switching-regulator output voltage can be
adjusted from V
tors R7 and R8. Refer to the Design Procedure, Step-
Up Regulator Design, Output-Voltage Selection section
in the MAX8728 data sheet. Operation at significantly
higher output voltages can reduce the available output
current, and may require changes in component values
or component voltage ratings.
The gate-on (VSRC) supply consists of two positive
charge-pump stages to generate +28V and can pro-
vide greater than 50mA. This output can be adjusted
from approximately V
feedback resistors R14 and R15. Refer to the Design
Procedure, Charge-Pump Regulators, Output-Voltage
Selection section in the MAX8728 data sheet.
The positive charge-pump regulator’s startup delay
time can be adjusted by replacing capacitor C11. Refer
to the Positive Charge-Pump Regulator and Power-Up
Sequence sections in the MAX8728 data sheet for
additional details.
The VGOFF supply consists of a single negative
charge-pump stage to generate -6V and can provide
greater than 150mA. This output can be adjusted from
approximately 0 to -V
R5 and R6. Refer to the Design Procedure, Charge-
Pump Regulators, Output-Voltage Selection section in
the MAX8728 data sheet.
The MAX8728 contains two high-voltage switches that
operate in a complementary fashion. One of the switches
provides a connection between the SRC and GON
pins. The other switch provides a connection between
the GON and DRN pins. Both switches can be con-
trolled by an external TTL square-wave signal connected
to the CTL pad.
When CTL is high, GON is connected to SRC, charging
GON to the voltage of the positive charge pump at the
VSRC pad. When CTL is low, GON may be connected
to DRN, allowing GON to discharge toward AVDD
IN
to +28V by replacing feedback resis-
IN
IN
by replacing feedback resistors
to nearly 3 x V
IN
by replacing
3