Rainbow-electronics MAX5974D Manual de usuario descargar pdf (Pagina 3)

MAX5974A/MAX5974B/MAX5974C/MAX5974D

Active-Clamped, Spread-Spectrum,

Current-Mode PWM Controllers

3

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

SYNCHRONIZATION (SYNC)

Synchronization Logic-High

Input

V

IH-SYNC

2.91 V

Synchronization Pulse Width 50 ns

Synchronization Frequency

Range

f

SYNCIN

1.1 x

f

SW

2 x

f

SW

kHz

Maximum Duty Cycle During

Synchronization

D

MAX

x f

SYNC

/

f

SW

%

DITHERING RAMP GENERATOR (DITHER)

Charging Current V

DITHER

= 0V 45 50 55

FA

Discharging Current V

DITHER

= 2.2V 43 50 57

FA

Ramp’s High Trip Point 2 V

Ramp’s Low Trip Point 0.4 V

SOFT-START AND RESTART (SS)

Charging Current I

SS-CH

9.5 10 10.5

FA

Discharging Current

I

SS-D

V

SS

= 2V, normal shutdown 0.65 1.34 2 mA

I

SS-DH

(V

EN

< V

ENF

or V

IN

< V

INUVF

),

V

SS

= 2V, hiccup mode discharge for

t

RESTART

(Note 3)

1.6 2 2.4

FA

Discharge Threshold to Disable

Hiccup and Restart

V

SS-DTH

0.15 V

Minimum Restart Time During

Hiccup Mode

t

RSTRT-MIN

1024

Clock

Cycles

Normal Operating High Voltage V

SS-HI

5 V

Duty-Cycle Control Range V

SS-DMAX

D

MAX

(typ) = (V

SS-DMAX

/2.43V) 0 2 V

DUTY-CYCLE CLAMP (DCLMP)

DCLMP Input Current I

DCLMP

V

DCLMP

= 0 to 5V -100 0 +100 nA

Duty-Cycle Control Range V

DCLMP-R

V

DCLMP

= 0.5V 73 75.4 77.5

%

D

MAX

(typ) =

1 - (V

DCLMP

/

2.43V)

V

DCLMP

= 1V 54 56 58

V

DCLMP

= 2V 14.7 16.5 18.3

NDRV DRIVER

Pulldown Impedance R

NDRV-N

I

NDRV

(sinking) = 100mA 1.9 3.4

I

Pullup Impedance R

NDRV-P

I

NDRV

(sourcing) = 50mA 4.7 8.3

I

Peak Sink Current 1 A

Peak Source Current 0.65 A

Fall Time t

NDRV-F

C

NDRV

= 1nF 14 ns

Rise Time t

NDRV-R

C

NDRV

= 1nF 27 ns

1 2 3 4 5 6 7 8 ... 25 26

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