Datasheet

MAX17595/MAX17596/MAX17597
Peak-Current-Mode Controllers for
Flyback and Boost Regulators
10Maxim Integrated
Pin Description (continued)
Detailed Description
The MAX17595 offers a bootstrap UVLO wake-up level
of 20V with a wide hysteresis, and is optimized for imple-
menting isolated and nonisolated universal (85V to 265V
AC) offline single-switch flyback converter or telecom
(36V to 72V) power supplies. The MAX17596/MAX17597
offer a UVLO wake-up level of 4.4V and are well-suited
for low-voltage DC-DC flyback/boost power supplies. An
internal 1% reference (1.21V) can be used to regulate
the output in nonisolated flyback and boost applications.
Additional semiregulated outputs, if needed, can be gen-
erated by using additional secondary windings on the
flyback converter transformer.
The MAX17595/MAX17596/MAX17597 family utilizes
peak-current-mode control and external compensation
for optimizing closed-loop performance. The devices
include cycle-by-cycle peak current limit, and eight
consecutive occurrences of current-limit-event trigger
hiccup mode, which protects external components by
halting switching for a period of 32,768 cycles. .
Input Voltage Range (V
IN
)
The MAX17595 has no limitation on maxi-
mum input voltage, as long as the external
components are rated suitably and the maximum
operating voltages of the MAX17595 are respected.
The MAX17595 implements a rising and falling UVLO
threshold that allows it to be successfully used in univer-
sal input (85V to 265V AC) rectified bus applications, in
rectified 3-phase DC bus applications, and in telecom
(36V to 72V DC) applications.
The MAX17596/MAX17597 are intended to implement
flyback (isolated and nonisolated) and boost convert-
ers. The V
IN
pin of the MAX17596/MAX17597 has a
maximum operating voltage of 36V. The MAX17596/
MAX17597 implement rising and falling thresholds on
the V
IN
pin that assume power-supply startup schemes
typical of low-voltage DC-DC applications, down to
an input voltage of 4.5V DC. Therefore, flyback/boost
converters with a 4.5V to 36V supply voltage range can
be implemented with the MAX17596/MAX17597.
Internal Linear Regulator (V
DRV
)
The internal functions and driver circuits are designed
to operate from 7.4V (MAX17595) or 5V (MAX17596/
MAX17597) power-supply voltages. The MAX17595/
MAX17596/MAX17597 family has an internal linear regu-
lator that is powered from the V
IN
pin. The output of the
linear regulator is connected to the V
DRV
pin, and should
be decoupled with a 1FF capacitor to ground for stable
operation. The V
DRV
regulator output supplies all the oper-
ating current of the MAX17595/MAX17596/MAX17597.
The maximum operating voltage on the V
IN
pin is 29V for
the MAX17595, and 36V for the MAX17596/MAX17597.
PIN NAME FUNCTION
13 VDRV
Linear Regulator Output and Driver Input. Connect a 1µF bypass capacitor from V
DRV
to SGND as
close as possible to the IC.
14 VIN
Internal V
DRV
Regulator Input. Connect V
IN
to the input voltage source. Bypass V
IN
to PGND with
a 1FF minimum ceramic capacitor.
15 EN/UVLO
Enable/Undervoltage Lockout. To externally program the UVLO threshold of the input supply,
connect a resistive divider between input supply, EN, and SGND.
16 OVI
Overvoltage Comparator Input. Connect a resistive divider between the input supply, OVI, and
SGND to set the input overvoltage threshold.
— EP
Exposed Pad. Connect to a large ground plane through multiple vias to maximize thermal
dissipation.