Electrical characteristics (continued) – Rainbow Electronics MAX5974D User Manual
Page 4
MAX5974A/MAX5974B/MAX5974C/MAX5974D
Active-Clamped, Spread-Spectrum,
Current-Mode PWM Controllers
4
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 12V (for MAX5974A/MAX5974C, bring V
IN
up to 21V 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
AUXDRV DRIVER
Pulldown Impedance
R
AUX-N
I
AUXDRV
(sinking) = 50mA
4.3
7.7
I
Pullup Impedance
R
AUX-P
I
AUXDRV
(sourcing) = 25mA
10.6
18.9
I
Peak Sink Current
0.5
A
Peak Source Current
0.3
A
Fall Time
t
AUX-F
C
AUXDRV
= 1nF
24
ns
Rise Time
t
AUX-R
C
AUXDRV
= 1nF
45
ns
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
AUXDRV rising to
NDRV rising
R
DT
= 10kI
40
ns
R
DT
= 100kI
310
360
420
CURRENT-LIMIT COMPARATORS (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
47
52
58
F
A
PWM COMPARATOR
Comparator Offset Voltage
V
PWM-OS
V
COMP
- V
CSSC
1.35
1.7
2
V
Current-Sense Gain
A
CS-PWM
D
V
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