Detailed Description - Analog Devices MAX17625 Manual

Evaluates:
MAX17625/MAX17626
Converters in Application

Detailed Description

The MAX17625/MAX17626 EV kits are designed to demonstrate the salient features of the MAX17625/MAX17626 power
converters. The EV kits consist of typical application circuits of two different converters. Each of these circuits are
electrically isolated from each other and hosted on the same printed circuit board (PCB). Each of these circuits can be
evaluated for its performance under different operating conditions by powering them from their respective input pins.
MODE Selection
The MAX17625/MAX17626 supports PWM and PFM modes of operation. In the EV kits, leave the jumpers (JU102, JU202) open for
operating the converters in PFM mode at light-load. Install shunts to configure the converters in PWM mode. See
(JU102 and JU202) settings. Refer to the Mode Selection section of the MAX17625/MAX17626 data sheet for more details.
Adjusting Output Voltage
The MAX17625 supports a 0.8V to 1.5V adjustable output voltage and the MAX17625 EV kit output voltage is preset to 1.2V.
The MAX17626 supports a 1.5V to 3.3V adjustable output voltage and the MAX17626 EV kit output voltage is preset to 3.3V.
For the MAX17625, the output voltage is programmed using the resistor divider R101 and R102 and for the MAX17626,
the output voltage is programmed using the resistor divider R201 and R202. Refer to the Adjusting Output Voltage section
in the MAX17625/MAX17626 data sheet for more details.
Output Capacitor Selection
The X7R ceramic capacitors are preferred due to their stability over temperature in industrial applications. For the MAX17625,
the required output capacitor (C106) is 22μF/6.3V and for the MAX17626, the required output capacitor (C206) is 10μF/10V.
Refer to the Output Capacitor Selection section in the MAX17625/MAX17626 data sheet for more details.
Input Capacitor Selection
The input capacitors C103 for the MAX17625 and C203 for the MAX17626 serve to reduce the current peaks drawn from
the input power supply and reduce switching frequency ripple at the input. Refer to the Input Capacitor Selection section
in the MAX17625/MAX17626 data sheet to choose input capacitance. A 2.2μF/10V input capacitor is chosen for both the
MAX17625 and MAX17626.
Hot Plug-In and Long cables
The MAX17625/MAX17626 EV kits PCB provides optional Tantalum capacitors (C102 for MAX17625 and C202 for
MAX17626, 47μF/8V) to dampen input-voltage peaks and oscillations that can arise during hot plug-in and/or due to long
input cables. These capacitors limit the peak voltage at the input of the device when the EV kits are powered directly from
a precharged capacitive source or an industrial backplane PCB. Long input cables between the input power source and
the EV kits circuit can cause input-voltage oscillations due to the inductance of the cables. The equivalent series
resistance (ESR) of the Tantalum capacitor helps damp out the oscillations caused by long input cables. Further,
capacitors (C101, C104, C105 for the MAX17625 and C201, C204, C205 for the MAX17626) placed near the input of the
board and near the IN pin of the converter helps in attenuating high-frequency noise.
Table 1. EN Jumper Description (JU101, JU201)
SHUNT POSITION
*Default Position
Table 2. MODE Jumper Description (JU102, JU202)
SHUNT POSITION
Not Installed*
*Default Position
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MAX17625/MAX17626 Evaluation Kits
EN PIN
Connected to V
IN
Connected to GND
MODE PIN
Connected to GND
Unconnected
Table 2
OUTPUT
Enabled
Disabled
MODE
Operates in PWM Mode in all load conditions
Operates in PFM Mode in light-load conditions
Analog Devices | 3
for jumpers