Datasheet

MAX15046B Evaluation Kit
Evaluates: MAX15046B
4 ______________________________________________________________________________________
Configuring the Output Voltage
The MAX15046B EV kit’s VOUT voltage can be recon-
figured between 0.6V to 0.85 x VIN. To configure the
MAX15046B EV kit’s output voltage, refer to the Setting
the Output Voltage section in the MAX15046 IC data
sheet for instructions on selecting new resistor values.
Capacitors C13–C16 and resistors R10 and R11 provide
a compensation network for VOUT on the MAX15046B
EV kit circuit.
Refer to the Inductor Selection, Input Capacitor, and
Compensation Design sections in the MAX15046 IC data
sheet to verify whether other components need replace-
ment for proper operation after reconfiguring the output
voltage.
Current-Limit Thresholds
The MAX15046B IC employs a current-sensing algorithm
using the low-side MOSFET on-resistance as a current-
sensing element to limit the inductor current. The induc-
tor current is sensed in the converter by sensing the volt-
age drop across the on-resistance (R
DSON
) of low-side
MOSFET N2. The MAX15046B EV kit’s valley and sink
current limits are set to 13.5A and 6.75A, respectively.
Resistor R9 sets VOUT valley current-limit voltage thresh-
old (V
ITH
) to 162mV. The sink current-limit voltage
threshold is approximately one-half the valley current-
limit voltage threshold. Use the following equation to
reconfigure the valley current-limit voltage threshold:
ITH
LIM
6
V 10
R ( )
50 10
−
×
Ω =
×
where V
ITH
is the valley current-limit voltage threshold in
volts and R
LIM
is R9 in ohms.
Refer to the Current-Limit Circuit (LIM) and Setting
the Valley Current Limit sections in the MAX15046 IC
data sheet for further instructions on computing the
MAX15046B EV kit valley and sink current limits.
Surface-mount PCB pads for resistor R8 are provided to
implement foldback current-limit capabilities if required.
Switching Frequency
The MAX15046B controller switching frequency is set
to 350kHz by resistor R14. Replace resistor R14 with a
new resistor value to program the switching frequency
between 100kHz and 1MHz. Use the following equa-
tion to calculate R14 when reconfiguring the switching
frequency:
9
7 2
SW SW
17.3 10
R14
f (1x10 )x(f )
−
×
=
+
where f
SW
is in hertz and R14 is in ohms.
When reconfiguring the EV kit controller switching fre-
quency, it may be necessary to change compensa-
tion network component to new values. Refer to the
Compensation Design section in the MAX15046 IC data
sheet for computing new compensation component
values.
Power-Good Output (PGOOD)
The MAX15046B EV kit provides a PGOOD PCB pad to
monitor the status of the U1 power-good output signal.
PGOOD is high when VOUT rises 94.5% (typ) above its
programmed output voltage. When VOUT falls below
92% (typ) of its nominal regulated voltage, PGOOD is
pulled low. The PGOOD signal is pulled up to VCC by
resistor R4.
Enable Control (JU2)
Jumper JU2 configures the MAX15046B EV kit’s output
enable for turn on/off control. Install a shunt on pins 1-2
of jumper JU2 to enable VOUT. Conversely, VOUT is
disabled when the shunt is placed across pins 2-3 of
jumper JU2. Alternatively, the MAX15046B IC enable pin
(EN) can be controlled by an external controller. Surface-
mount PCB pads for optional capacitor C17 are included
to filter noise that may be introduced on the EN pin.
Table 2. Enable Control (JU2)
SHUNT
POSITION
EN PIN VOUT OUTPUT
1-2
Connected to VCC
through R3
Enabled
2-3 Pulled down to GND Disabled
Not installed External controller
External controller
enables/disables