MAX8739EVKIT Maxim Integrated Products, MAX8739EVKIT Datasheet - Page 3

• Manufacturer Part Number: MAX8739EVKIT
• Description: Display Modules & Development Tools MAX8739 KIT MAX8739 KIT
• Manufacturer: Maxim Integrated Products

Specifications of MAX8739EVKIT

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

The MAX8739 EV kit contains a step-up switching regu-
lator, a positive two-stage charge pump, a negative sin-
gle-stage charge pump, two operational amplifiers, and
a high-voltage switch matrix. The EV kit operates from a
DC power supply between +1.8V and +5.5V.
As configured, the step-up switching regulator (VMAIN)
generates a +8V output and can provide at least 200mA
from a +1.8V input. It also provides at least 260mA from
a 2.2V input and 370mA from a 3.0V input. Loading the
charge pumps reduces the available VMAIN output cur-
rent. The step-up switching-regulator output voltage can
be adjusted up to +13V with other feedback resistors
(see the Output-Voltage Selection section).
The GON consists of two positive charge-pump stages
to generate approximately +22V and can provide
greater than 20mA. The GOFF consists of a single neg-
ative charge-pump stage to generate approximately
-7V and can provide greater than 20mA. GOFF reduces
the available VMAIN current proportionally. Loading
GON reduces the available VMAIN current by 3 times
GON load.
The operational amplifier outputs, VOUT1 and VOUT2,
are set to +4V and can source or sink approximately
150mA. These two outputs can be reconfigured to other
voltages with voltage-divider resistors R3–R6 (see the
Output-Voltage Selection section).
The high-voltage switch between the SRC and COM pins
can be used to delay the GON startup. The GON voltage
is connected to the source of the switch (SRC) and the
drain of the switch (COM) is used as an output. The start-
up delay time is set with an external capacitor, C10, at
the DEL pin. Refer to the Switch Control and Delay sec-
tion in the MAX8739 data sheet for information on setting
the delay time.
The switch between the SRC and COM pins and the
switch between the COM and DRN pins can be con-
trolled by jumper JU2 or by an external TTL logic
source connected to the CTL pad. See Table 2 for
switch states and refer to the Switch Control and Delay
section in the MAX8739 data sheet for further informa-
tion about the high-voltage switches connected to the
COM pin.
The MAX8739 EV kit features an option to choose the
step-up regulator switching frequency. Jumper JU1
selects the switching frequency. Table 1 lists the selec-
table jumper options. The EV kit is configured for 1.2MHz
operation. Optimum performance at lower frequencies
Switching Frequency Selection (FREQ)
_______________________________________________________________________________________
Detailed Description
Jumper Selection
MAX8739 Evaluation Kit
Table 1. Jumper JU1 Functions
requires a larger inductor value (refer to the Inductor
Selection section in the MAX8739 data sheet). To set
the switching frequency at 600kHz, install a short
across JU1.
The MAX8739 EV kit features an option to control the
high-voltage switches between SRC, COM, and DRN
Table 2. Jumper JU2 Functions
on the MAX8739. Table 2 lists the selectable JU2
jumper options.
The MAX8739 EV kit’s step-up switching-regulator out-
put (VMAIN) is set to +8V by feedback resistors R1 and
R2. To generate output voltages other than +8V (up to
+13V), select different external voltage-divider resis-
tors, R1 and R2. Note that changing the VMAIN voltage
setting changes the GON and GOFF charge-pump out-
put voltages. Also, output capacitors C4 and C5 are
rated for +10V. To set the output voltage greater than
+10V, use higher voltage-rated capacitors. Refer to the
Output-Voltage Selection section in the MAX8739 data
sheet for instructions on selecting resistors R1 and R2.
LOCATION
Installed
(default)
SHUNT
LOCATION
None
None
(default)
Installed
SHUNT
None
Step-Up Switching Regulator Output
High-Voltage Switch Control (CTL)
GND through R8
Output-Voltage Selection
Connected to
Connected to
Connected to
external TTL
CTL PIN
source
Connected to GND
Connected to VIN
VIN
through R7
FREQ PIN
COM connected to SRC
(GON = +22V)
COM connected to DRN
Logic-low, COM connected
to DRN; logic-high,
COM connected to SRC
(GON = +22V)
Voltage (VMAIN)
MAX8739 COM
MAX8739 EV KIT
OUTPUT
FREQUENCY
1.2MHz
600kHz
3