Typical operating characteristics (continued) – Rainbow Electronics MAX8720 User Manual
Page 8
MAX8720
Dynamically Adjustable 6-Bit VID
Step-Down Controller
8
_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(MAX8720 Circuit of Figure 1, V
IN
= 12V, V
DD
= V
CC
= 5V, TON = open, T
A
= +25°C, unless otherwise noted.)
2ms/div
V
CC
UVLO WAVEFORM
1.25V
MAX8720 toc10
0
0
0
5V
4V
A
B
C
D
I
OUT
= 1A
A = V
OUT
, 500mV/div
B = V
CC
, 2V/div
C = DL, 5V/div
D = PGOOD, 5V/div
20
µs/div
LOAD TRANSIENT
(SKIP MODE)
1.25V
MAX8720 toc11
0
10A
0
0
12V
A
B
C
D
SKIP = GND, I
OUT
= 1A TO 11A TO 1A
A = V
OUT
, 50mV/div
B = LX, 10V/div
C = CONTROL, 5V/div
D = INDUCTOR CURRENT, 10A/div
20
µs/div
LOAD TRANSIENT
(PWM MODE)
1.25V
MAX8720 toc12
0
10A
0
0
12V
A
B
C
D
SKIP = V
CC
, I
OUT
= 1A TO 11A TO 1A
A = V
OUT
, 50mV/div
B = LX, 10V/div
C = CONTROL, 5V/div
D = INDUCTOR CURRENT, 10A/div
50
µs/div
DYNAMIC OUTPUT VOLTAGE TRANSITION
(SKIP MODE)
1.65V
MAX8720 toc13
0
10A
0
0
1.25V
12V
A
B
C
D
SKIP = GND, I
OUT
= 0.2A
A = V
OUT
, 200mV/div
B = LX, 10V/div
C = D4, 5V/div
D = INDUCTOR CURRENT, 10A/div
-10A
500
µs/div
STARTUP WAVEFORMS (NO LOAD)
1.25V
MAX8720 toc08
0
0
0
0
5V
5A
-5A
A
B
C
D
I
OUT
= NO LOAD
A = V
OUT
, 500mV/div
B = PGOOD, 5V/div
C = SHDN, 5V/div
D = INDUCTOR CURRENT, 5A/div
500
µs/div
STARTUP WAVEFORMS (HEAVY LOAD)
1.25V
MAX8720 toc09
0
0
0
0
5V
10A
A
B
C
D
I
OUT
= 10A
A = V
OUT
, 500mV/div
B = PGOOD, 5V/div
C = SHDN, 5V/div
D = INDUCTOR CURRENT, 10A/div