Rainbow Electronics MAX8775 - Manual (Page 8)

MAX8775
Dual and Combinable Graphics Core
Controller for Notebook Computers
8 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V IN = 12V, V DD = V CC = 5V, SKIP_ = GND, T
A = +25°C, unless otherwise noted.)
STARTUP WAVEFORMS
MAX8775 toc10
0
0
5A
200 μs/div
0
0
A
B
D
C
E
0
D: PGOOD1, 5V/div
E: I
LX1 , 5A/div
A: ON1, 5V/div
B: DL1, 5V/div
C: V
OUT1 , 1V/div
SKIP1 = GND, R LOAD1 = 1 Ω, V
IN = 12V
SHUTDOWN WAVEFORMS
MAX8775 toc11
0
1.5V
0
5A
0
0
A
B
D
C
E
0
D: PGOOD1, 5V/div
E: I
LX1
, 5A/div
A: ON1, 5V/div
B: DL1, 5V/div
C: V
OUT1 , 1V/div
SKIP1 = GND, R LOAD1 = 1 Ω, V
IN = 12V
200 μs/div
STARTUP/SHUTDOWN—
SAME SLEW RATE
0
0
5V
5V
0
0
A
B
D
C
E
0
D: PGOOD1, 5V/div
E: PGOOD2, 5V/div A: ON1, ON2, 5V/div
B: V
OUT1 , 1V/div
C: V OUT2 , 1V/div
C SLEW1 = C SLEW2 = 470pF
R LOAD1 = R LOAD2 = 1 Ω
400 μs/div
MAX8775 toc12
STARTUP/SHUTDOWN—
SAME START TIME
MAX8775 toc13
0
0
5V
5V
0
400 μs/div
0
A
B
D
C
E
0
D: PGOOD1, 5V/div
E: PGOOD2, 5V/div A: ON1, ON2, 5V/div
B: V
OUT1 , 1V/div
C: V OUT2 , 1V/div
C SLEW1 = 470pF, C SLEW2 = 600pF
R LOAD1 = R LOAD2 = 1 Ω
LOAD TRANSIENT (SEPARATE MODE)
MAX8775 toc14
0
10A
5V
0
20 μs/div
1.2V
12V
A
B
D
C
0
C: LX1, 10V/div
D: I
LX1 , 10A/div
A: V
OUT1
, 100mV/div
B: DL1, 5V/div
V IN = 12V, V OUT1 = 1.2V
SKIP1 = GND
I
OUT1 = 1A TO 11A TO 1A
LOAD TRANSIENT (COMBINED MODE)
MAX8775 toc15
0
10A
0
1.5V
12V
12V
A
B
D
C
0
C: LX1, 10V/div
D: LX2, 10V/div A: V
OUT1
, 100mV/div
B: I LX1 , 10A/div
V IN = 12V, V OUT = 1.5V
I OUT1 = 5A TO 25A TO 5A
20 μs/div