MAX5069AAUE View Datasheet(PDF) - Maxim Integrated
Part Name
Description
MFG CO.
MAX5069AAUE
Maxim Integrated
MAX5069AAUE Datasheet PDF : 19 Pages
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High-Frequency, Current-Mode PWM Controller
with Accurate Oscillator and Dual FET Drivers
D3
D1
VIN
R2
C2
C3
C4
R3
R4
C5
R1
C1
FLTINT
IN
UVLO/EN
VCC
HYST
MAX5069B
REG5
R6
RHYST
R7
RT
NDRVB
NDRVA
Q1
DT
CS
SCOMP
FB
R8
AGND PGND COMP
R5
C6
D2
Q2
Figure 1. Nonisolated Power Supply with Programmable Input Supply Voltage
VOUT
C7
R9
R10
Undervoltage Lockout
The MAX5069 features an input voltage UVLO/EN func-
tion to enable the PWM controller before any operation
can begin. The MAX5069A/D shut down if the voltage
at UVLO/EN falls below its 1.18V threshold. The
MAX5069B/C also incorporate a UVLO hysteresis input
to set the desired turn-off voltage.
MAX5069A/D UVLO Adjustment
The MAX5069A/D have an input voltage UVLO/EN with
a 1.231V threshold. Before any operation can com-
mence, the UVLO/EN voltage must exceed the 1.231V
threshold. The UVLO circuit keeps the PWM compara-
tor, ILIM comparator, oscillator, and output drivers shut-
down to reduce current consumption (see the
Functional Diagram).
Calculate R6 in Figure 2 by using the following formula:
R6
=
⎛
⎝⎜
VON
VULR2
⎞
− 1⎠⎟ ×
R7
where VULR2 is the UVLO/EN’s 1.231V rising threshold
and VON is the desired startup voltage. Choose an R7
value in the 20kΩ range.
After a successful startup, the MAX5069A/D shut down
if the voltage at UVLO/EN drops below its 1.18V fall-
ing threshold.
MAX5069B/C UVLO with
Programmable Hysteresis
In addition to programmable undervoltage lockout dur-
ing startup, the MAX5069B/C incorporate a UVLO/EN
10 ______________________________________________________________________________________
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