Datasheet

5Maxim Integrated
Active-Clamped, Spread-Spectrum,
Current-Mode PWM Controllers
MAX5974A/MAX5974B/MAX5974C/MAX5974D
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 12V (for MAX5974A/MAX5974C, bring V
IN
up to 17V for startup), V
CS
= V
CSSC
= V
DITHER/SYNC
= V
FB
= V
FFB
= V
DCLMP
=
V
GND
, V
EN
= +2V, NDRV = AUXDRV = SS = COMP = unconnected, R
RT
= 34.8kI, R
DT
= 25kI, C
IN
= 1FF, T
A
= -40NC to +85NC,
unless otherwise noted. Typical values are at T
A
= +25NC.) (Note 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DEAD-TIME PROGRAMMING (DT)
DT Bias Voltage V
DT
1.215 V
NDRV to AUXDRV Delay
(Dead Time)
t
DT
From NDRV falling
to AUXDRV falling
R
DT
= 10kI 40
ns
R
DT
= 100kI 300 350 410
From AUXDRV rising
to NDRV rising
R
DT
= 10kI 40
ns
R
DT
= 100kI 310 360 420
CURRENT-LIMIT COMPARATOR (CS)
Cycle-by-Cycle Peak
Current-Limit Threshold
V
CS-PEAK
375 393 410 mV
Cycle-by-Cycle Reverse
Current-Limit Threshold
V
CS-REV
Turns AUXDRV off for the remaining
cycle if reverse current limit is exceeded
-118 -100 -88 mV
Current-Sense Blanking Time
for Reverse Current Limit
t
CS-BLANK-
REV
From AUXDRV falling edge 115 ns
Number of Consecutive Peak
Current-Limit Events to Hiccup
N
HICCUP
8 Events
Current-Sense Leading-Edge
Blanking Time
t
CS-BLANK
From NDRV rising edge 115 ns
Propagation Delay from
Comparator Input to NDRV
t
PDCS
From CS rising (10mV overdrive) to
NDRV falling (excluding leading-edge
blanking)
35 ns
Minimum On-Time t
ON-MIN
100 150 200 ns
SLOPE COMPENSATION (CSSC)
Slope Compensation Current
Ramp Height
Current ramp’s
peak added to
CSSC input per
switching cycle
-40°C to +85°C 47 52 58
FA
-40°C to +125°C 46.5 52 59.5
PWM COMPARATOR
Comparator Offset Voltage V
PWM-OS
V
COMP
- V
CSSC
-40°C to +85°C 1.35 1.7 2
V
-40°C to +125°C 1.34 1.7 2
Current-Sense Gain A
CS-PWM
DV
COMP
/DV
CSSC
(Note 4) 3.1 3.33 3.6 V/V
Current-Sense Leading-Edge
Blanking Time
t
CSSC-BLANK
From NDRV rising edge 115 ns
Comparator Propagation Delay t
PWM
Change in V
CSSC
= 10mV (including
internal leading-edge blanking)
150 ns