MAX5969AEVKIT# Maxim Integrated, MAX5969AEVKIT# Datasheet - Page 5

• Manufacturer Part Number: MAX5969AEVKIT#
• Description: Power Management IC Development Tools MAX5969A Eval Kit
• Manufacturer: Maxim Integrated
• Series: MAX5969A, MAX5969Br

Specifications of MAX5969AEVKIT#

• Rohs: yes

The EV kit’s 12W, 300kHz flyback DC-DC converter uses
a MAX5974A inductive-feedback current-mode PWM
controller. The MAX5969A’s VDD and RTN pins provide
power for the DC-DC converter input circuit. The DC-DC
converter is configured for an output voltage of +12V
and provides up to 1A of output load current. The EV kit
circuit achieves up to 92% efficiency using MOSFET N2
for synchronous rectification on the secondary side. An
additional MOSFET N3 (SOT23) PCB pad is available
for increasing the output current load up to 2A with a
switching frequency of 400kHz. Transistor Q2 is provided
to limit the output overshoot at startup. Surface-mount
transformer T1 provides up to 1500V galvanic isolation
for the isolated output. Current-sense resistors R21 and
R25 limit the peak current through transistor N1 and
the primary of transformer T1. Primary-side feedback
regulation is achieved using T1 auxiliary winding and
voltage feedback resistors R3, R8, and R12 to set the
isolated output voltage. Diodes D6 and D7 are provided
for limiting the voltage spikes across transformer T1
during N1 turn-off time. The EV kit also includes additional
circuitry with uninstalled PCB pads to reconfigure the EV
kit using optocoupler feedback. See the Reconfiguring
the EV Kit for Optocoupler Feedback section for
additional information.
The EV kit is configured for a Class 3 (6.49W to 12.95W)
PD classification by resistor R4. To reconfigure the PD
classification, replace surface-mount (0805) resistor R4.
Table 1 lists the PD classification options.
The EV kit can also accept power from a wall adapter
power source. Use the WAD_IN and WAD_GND (+30V
to +57V) PCB pads to connect the wall adapter power
source. The wall adapter power-source operating-volt-
age range must be within +36V to +57V for the EV kit.
When the wall adapter power source is above +36V, it
takes precedence over the PSE source. Once the wall
adapter power source is detected, The MAX5969A (U1)
internal isolation switch disconnects VSS from RTN. The
wall adapter power is supplied to VDD (through diode
D4 and RTN). Once it takes over, the PD internal switch
is turned off. Resistors R27 and R28 are available for
adjusting the EV kit wall adapter voltage for disabling the
PSE source.
_________________________________________________________________ Maxim Integrated Products 5
PD Classification Signature
Wall Adapter Power Source
(WAD_IN, WAD_GND)
Evaluates: MAX5969A/MAX5974A
If the wall adapter power source is below +27V, the PSE
provides power through the device’s RTN after a suc-
cessful detection and classification. Diode D4 prevents
the PSE from backdriving the wall adapter power source.
The EV kit features Ethernet jack J1 to interface with
the Ethernet data signals. J1 is provided for interfacing
the EV kit with the Ethernet data signals only. Refer to
the RJ45 MagJack data sheet on the Bel Fuse website
prior to interfacing the EV kit’s J1 jack with the Ethernet
data signals.
The EV kit also supports an isolated DC-DC converter
design using optocoupler feedback. On the transformer’s
secondary side, PCB footprint pads are available for
shunt regulator U4, along with additional resistors and
capacitor components, providing secondary-side volt-
age feedback to the primary side through optocoupler
U3. The MAX5974A receives the voltage feedback signal
on the primary side from biasing resistors R51, R53, and
R54. When reconfiguring the EV kit for optocoupler feed-
back, the following modifications must be made:
• Remove components R3, R8, and R12 (primary-side
• Install optocoupler U3 (4-pin DIP footprint)
• Install shunt regulator U4 (5-pin SOT23 footprint)
• Install required surface-mount (0402/0603) resistor
Table 1. PD Classification Selection
CLASS
feedback regulation components)
and capacitor components for feedback regulation.
0
1
2
3
4
5
Ethernet Data-Signal Interfacing
MAXIMUM POWER
USED BY PD (W)
0.44 to 12.95
6.49 to 12.95
12.95 to 25.5
Reconfiguring the EV Kit for
0.44 to 3.84
3.84 to 6.49
> 25.5
Optocoupler Feedback
RESISTOR
R4 (I)
66.5
43.2
30.9
21.3
619
118