MAX1778EVKIT Maxim Integrated Products, MAX1778EVKIT Datasheet - Page 3

• Manufacturer Part Number: MAX1778EVKIT
• Description: Power Management Modules & Development Tools MAX1778 EVAL KIT MAX1778 EVAL KIT
• Manufacturer: Maxim Integrated Products

Specifications of MAX1778EVKIT

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

The positive charge-pump circuit can be reconfigured
to provide up to +35V by changing feedback resistors,
provided that the step-up switching regulator (V1) has
been changed to a higher voltage. The negative
charge-pump circuit can also be reconfigured to pro-
vide up to -11V by changing feedback resistors, pro-
vided that the step-up switching regulator (V1) has
been adjusted to a higher voltage.
The EV kit’s LDO linear regulator circuit is configured
for a +2.5V output (LDOOUT) at more than 200mA of
current and can be reconfigured for other output volt-
ages by replacing feedback resistors. When using an
external transistor (Q1) for the LDO, regulator power for
the LDO output is provided by PIN. When an external
transistor (Q1) is not used, power is provided by the
step-up switching regulator (V1). For even higher out-
put current, the SOT23 NPN transistor (Q1) can be
replaced with a larger D-PAK device.
The V
voltage of the step-up switching regulator (V1) and can
be reconfigured for other voltages by replacing the volt-
age-divider resistors (R10, R11). The step-up switching
regulator provides power to the V
rate analog ground pad (GND) for the V
put is provided to reduce noise coupling to the output.
The EV kit features an adjustable fault-trip level that can
be reconfigured for different fault-trip levels.
Unpopulated feedback-compensation PC board pads
are provided for the step-up switching regulator. The lin-
ear regulator can be configured for different voltages
and output currents.
The MAX1778 EV kit can also evaluate the MAX1880,
MAX1881, and MAX1882. Order the IC from the phone
number listed on page 1, and replace the MAX1778 with
the appropriate IC.
The MAX1778 EV kit features a shutdown mode that
reduces the MAX1778 quiescent current.
The 2-pin jumper (JU1) selects the MAX1778 shutdown
mode. Table 1 lists the selectable jumper options.
The MAX1778 EV kit’s step-up switching-regulator out-
put is set to +8V by feedback resistors (R1, R2). To
generate output voltages other than +8V (up to +13V),
select different external voltage-divider resistors (R1,
R2). The ceramic capacitors (C17, C18, C21) are rated
COM
Output Voltage Selection and
Jumper Selection Shutdown Mode
buffer output (BUFOUT) is a scaled down
_______________________________________________________________________________________
Regulator Output Voltages
Transient Load Test
Step-Up Switching-
COM
buffer. A sepa-
COM
buffer out-
MAX1778 Evaluation Kit
to +10V, so replace them with higher voltage-rated
capacitors for output voltages over 10V. Refer to the
Output Voltage Selection section in the MAX1778 data
sheet for instructions on selecting the resistors.
The MAX1778 EV kit’s positive charge-pump regulator
output is set to +20V by feedback resistors (R3, R4). To
generate output voltages other than +20V (up to +35V),
select different external voltage-divider resistors (R3,
R4). Refer to the Output Voltage Selection section in the
MAX1778/MAX1880–MAX1885 data sheet for instruc-
tions on selecting the resistors. Check that the capaci-
tor voltage rating is adequate for the configuration.
The MAX1778 EV kit’s negative charge-pump regulator
output is set to -5V by feedback resistors (R5, R6). To
generate output voltages other than -5V (down to -11V),
select different external voltage-divider resistors (R5,
R6). Refer to the Output Voltage Selection section in the
MAX1778/MAX1880–MAX1885 data sheet for instruc-
tions on selecting the resistors.
The MAX1778 EV kit’s LDO linear regulator output is set
to +2.5V by feedback resistors (R14, R15). To generate
output voltages other than +2.5V (+1.25V to V
-300mV), select different external voltage-divider resis-
tors (R14, R15). Refer to the Output Voltage Selection
section in the MAX1778 data sheet for instructions on
selecting the resistors. The power dissipation of the
NPN transistor (Q1, 350mW) must not be exceeded. If
a larger transistor is required, a “DPAK” surface-mount
case may be used to replace Q1 (MJD31, On
Semiconductor, or similar recommended). Refer to the
External Pass Transistor section in the MAX1778/
MAX1880–MAX1885 data sheet for instructions on
selecting a transistor.
The MAX1778 EV kit’s V
configured to one half of V1’s output voltage (i.e., 0.5
8V = +4V) by using the MAX1778 IC’s internal 0.5 volt-
Table 1. Jumper JU1 Functions
LOCATION
Negative Charge-Pump Output Voltages
Installed
Positive Charge-Pump Output Voltages
SHUNT
None
LDO Regulator Output Voltages
V
through R8
Connected to PIN
Connected to GND
COM
COM
SHDN
Buffer Output Voltages
PIN
buffer output (BUFOUT) is
Enabled
Shutdown
MAX1778
OUTPUT
PIN
3
✕