Datasheet

Evaluates: MAX1889
Negative Charge Pump
The negative charge pump of the MAX1889 EV kit fea-
tures an option to cascade up to three stages of charge
pumps. Each stage of the charge pump can be pow-
ered from INPUT, PGND, or the previous stage. JU3,
JU4, and JU5 configure the number of stages and
select the voltage source for the negative charge pump
on the MAX1889 EV kit. Tables 6, 7, and 8 list the
jumper options. The default configuration of the nega-
tive charge pump of the MAX1889 EV kit is a one-stage
charge pump powered from PGND as indicated in
Table 8. Refer to the Charge Pumps section of the
MAX1889 data sheet for information on selecting a
charge-pump configuration.
Output Voltage Selection
Step-Up Switching-Regulator
Output Voltage
The MAX1889 EV kit’s step-up switching-regulator out-
put is set to 9V by feedback resistors R5 and R6. To
generate output voltages other than 9V (up to 13V),
select different external voltage-divider resistors (R5,
R6). The output capacitors (C4, C5, and C6) are rated
to 10V. To set the output voltage greater than 10V, use
higher-voltage rated capacitors. Refer to the Main Step-
Up Regulator, Output Voltage Selection section in the
MAX1889 data sheet for instructions on selecting the
resistors.
MAX1889 Evaluation Kit
4 _______________________________________________________________________________________
SHUNT
LOCATION
SECOND STAGE
POSITIVE CHARGE
PUMP
OPERATING
MODE
1-2
(Default)
Connected to VBST
First stage of a two-
stage charge pump
powered by VBST
1-3
Connected to previous
stage charge-pump
output
Second stage of a
three-stage charge
pump
1-4 Connected to INPUT
First stage of a two-
stage charge pump
powered by INPUT
None Not used
Not used for one-stage
charge pumps
Table 4. JU7 Functions
SHUNT
LOCATION
FIRST STAGE
POSITIVE CHARGE
PUMP
OPERATING MODE
1-2 Connected to VBST
First stage of a three-
stage charge pump
powered by VBST
2-3 Connected to INPUT
First stage of a three-
stage charge pump
powered by INPUT
None Not used
Not used for one-stage
or two-stage charge
pumps
Table 3. JU8 Functions
SHUNT
LOCATION
SHDN PIN MAX1889 EV KIT OUTPUT
Installed
Connected
to PGND
Shutdown mode
None
Connected to IN
through R3
MAX1889 enabled
None
External controller
connected
to SHDN pad
Logic high (IN) = enabled,
logic low (PGND) = disabled
Table 1. JU1 Functions Table 2. JU2 Functions
SHUNT
LOCATION
FREQ PIN
MAX1889 EV KIT
FREQUENCY
Installed
Connected
to PGND
Frequency = 500KHz
None
Connected to
IN through R4
Frequency = 1MHz