MAX5069EVKIT Maxim Integrated Products, MAX5069EVKIT Datasheet - Page 11

• Manufacturer Part Number: MAX5069EVKIT
• Description: EVAL KIT FOR MAX5069
• Manufacturer: Maxim Integrated Products

Specifications of MAX5069EVKIT

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Isolated
• Voltage - Output: 12V
• Current - Output: 10A
• Voltage - Input: 36 ~ 72V
• Regulator Topology: Buck
• Frequency - Switching: 500kHz
• Board Type: Fully Populated
• Utilized Ic / Part: MAX5069
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Figure
Threshold
hysteresis that allows the user to set a voltage (V
disable the controller (see
At the beginning of the startup sequence, UVLO/EN is
below the 1.23V threshold, and Q1 turns on connecting
R
old is crossed, Q1 turns off, resulting in the series com-
bination of R6, R
normal operating condition.
Calculate the turn-on voltage (V
lowing formula:
where V
Choose an R
The MAX5069 turns off when the MAX5069 UVLO/EN
falls below the 1.18V falling threshold. The turn-off volt-
age (V
where V
In addition to the externally programmable UVLO func-
tion offered by the MAX5069, the MAX5069A/B feature
an additional internal bootstrap UVLO for use in high-
voltage power supplies (see the Functional Diagram).
This allows the device to bootstrap itself during initial
HYST
High-Frequency, Current-Mode PWM Controller
with Accurate Oscillator and Dual FET Drivers
OFF
2. Setting the MAX5069A/D Undervoltage Lockout
to GND
ULR2
ULF2
) is then defined as:
R
HYST
is the 1.18V UVLO/EN falling threshold.
Bootstrap Undervoltage Lockout
is the UVLO/EN’s 1.23V rising threshold.
7
R
(Figure
6
=
HYST
MAX5069A/D
______________________________________________________________________________________
value in the 20kΩ range.
=
R
6
⎛
⎜
⎝
, and R7, placing the MAX5069 in
/
4). Once the UVLO 1.23V thresh-
V
⎛
⎜
⎝
V
ULR
V
ON
V
ULF
Figure
OFF
2
1.23V
1.18V
2
−
1
−
⎞
⎟ ×
⎠
3).
ON
1
UVLO/EN
⎞
⎟
⎠
) by using the fol-
−
(MAX5069A/B)
R
R
HYST
HYST
V
IN
R6
R7
OFF
) to
power-up. The MAX5069A/B start when V
the bootstrap UVLO threshold of 23.6V.
During startup, the UVLO circuit keeps the PWM com-
parator, ILIM comparator, oscillator, and output drivers
shut down to reduce current consumption. Once V
reaches 23.6V, the UVLO circuit turns on both the PWM
and ILIM comparators, as well as the oscillator, and
allows the output driver to switch. If V
9.7V, the UVLO circuit shuts down the PWM compara-
tor, ILIM comparator, oscillator, and output drivers,
returning the MAX5069A/B to the startup mode.
Figure
Figure
4. Setting the MAX5069B/C Turn-On/Turn-Off Voltages
3. MAX5069 Hysteresis
MAX5069B/C
V
OFF
V
HYST
1.23V
1.18V
= V
ON
- V
Q1
OFF
UVLO/EN
HYST
V
ON
IN
drops below
V
IN
IN
R6
R
R7
HYST
exceeds
11
IN