Datasheet

MAX17499/MAX17500
Current-Mode PWM Controllers with
Programmable Switching Frequency
4 _______________________________________________________________________________________
Note 1: All devices are 100% tested at T
A
= +125°C. All limits over temperature are guaranteed by characterization.
Note 2: The MAX17500 is intended for use in universal input power supplies. The internal clamp circuit at IN is used to prevent the
bootstrap capacitor (C1 in Figure 1) from charging to a voltage beyond the absolute maximum rating of the device when
UVLO/EN is low (shutdown mode). Externally limit the maximum current to IN (hence to clamp) to 2mA maximum when
UVLO/EN is low. Clamp currents higher than 2mA may result in a clamp voltage higher than 30V, thus exceeding the
absolute maximum rating for IN. For the MAX17499, do not exceed the 24V maximum operating voltage of the device.
Note 3: V
REF
is measured with FB connected to COMP (see the Functional Diagram ).
Note 4: The oscillator in the MAX17499A/MAX17500A is capable of operating up to 2500kHz. However, the NDRV switching fre-
quency is limited to operate up to 625kHz. Thus, the oscillator frequency for the MAX17499A/MAX17500A must be limited to
1250kHz (maximum).
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +12V (for MAX17500, bring V
IN
up to 23.6V for startup), 10nF bypass capacitors at IN and V
CC
, R12 = 15kΩ (MAX17499A/
MAX17500A), R12 = 7.5kΩ (MAX17499B/MAX17500B), R15 = 1kΩ, C6 = 100nF (see the
Typical Application Circuit ), NDRV = open,
V
UVLO/EN
= +1.4V, V
FB
= +1.0V, COMP = open, V
CS
= 0V, T
A
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
=
+25°C.) (Note 1)
BOOTSTRAP UVLO WAKE-UP LEVEL
vs. TEMPERATURE
MAX17499/500 toc01
TEMPERATURE (°C)
V
IN
(V)
603510-15
21.4
21.5
21.6
21.7
21.8
21.3
-40
85
MAX17500 V
IN
RISING
BOOTSTRAP UVLO SHUTDOWN LEVEL
vs. TEMPERATURE
MAX17499/500 toc02
TEMPERATURE (°C)
V
IN
(V)
603510-15
9.5
9.7
9.9
10.1
10.3
9.3
-40
85
MAX17500 V
IN
FALLING
UVLO/EN WAKE-UP THRESHOLD
vs. TEMPERATURE
MAX17499/500 toc03
TEMPERATURE (°C)
V
UVLO/EN
(V)
603510-15
1.226
1.228
1.230
1.232
1.234
1.236
1.224
-40 85
UVLO/EN RISING
Typical Operating Characteristics
(V
UVLO/EN
= +1.4V, V
FB
= +1V, COMP = open, V
CS
= 0V, T
A
= +25°C, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
OSCILLATOR
Oscillator Frequency Range f
OSC
50 2500 kHz
f
OSC
= 200kHz to 800kHz -10 +10
Oscillator Frequency Accuracy
f
OSC
= 50kHz to 2500kHz -20 +20
%
MAX17499A/MAX17500A, f
SW
= f
OSC
/2 25 625
NDRV Switching Frequency
(Note 4)
f
SW
MAX17499B/MAX17500B, f
SW
= f
OSC
/4 12.5 625.0
kHz
MAX17499A/MAX17500A 50
Maximum Duty Cycle D
MAX
MAX17499B/MAX17500B 75
%