Datasheet

MAX1997/MAX1998
Quintuple/Triple-Output TFT LCD Power Supplies
with Fault Protection and VCOM Buffer
8 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
IN
= 3.3V, V
MAIN
= 9V, V
G_ON
= 20V, V
G_OFF
= -7V, V
LOGIC
= 2.5V, V
GAMMA
= 8.6V, T
A
= +25°C,
unless otherwise noted.)
STEP-UP REGULATOR LOAD TRANSIENT RESPONSE
(WITH LAG COMPENSATION, FIGURE 9)
MAX1997 toc08
10µs/div
B
A
C
0.5A
200mA
0
1A
8.9V
9V
0
A: I
MAIN
= 0 TO 200mA, 200mA/div
B: V
MAIN
= 9V, 50mV/div, AC-COUPLED
C: INDUCTOR CURRENT, 500mA/div
R7 = 76.8kΩ, R8 = 12.1kΩ, R10 = 1.5kΩ, C10 = 470pF
STEP-UP REGULATOR LOAD TRANSIENT RESPONSE
(2
µs PULSES)
(WITHOUT LAG COMPENSATION, FIGURE 1)
MAX1997 toc09
4µs/div
B
A
C
1A
1A
0
2A
8.9V
9V
50mA
A: I
MAIN
= 50mA TO 1A, 1A/div
B: V
MAIN
= 9V, 100mV/div, AC-COUPLED
C: INDUCTOR CURRENT, 1A/div
STEP-UP REGULATOR LOAD TRANSIENT RESPONSE
(2
µs PULSES)
(WITH LAG COMPENSATION, FIGURE 9)
MAX1997 toc10
10µs/div
B
A
C
1A
1A
0
2A
8.9V
9V
50mA
A: I
MAIN
= 50mA TO 1A, 1A/div
B: V
MAIN
= 9V, 100mV/div, AC-COUPLED
C: INDUCTOR CURRENT, 1A/div
R7 = 76.8kΩ, R8 = 12.1kΩ, R10 = 1.5kΩ, C10 = 470pF
STEP-UP REGULATOR SOFT-START
MAX1997 toc11
1ms/div
B
A
C
5V
5V
0
10V
0
5V
0
A: V
SHDN
, 5V/div
B: V
GATE
, 5V/div
C: V
DRAIN
, 5V/div
D: V
MAIN
, 5V/div
D
5V
0
POWER-UP SEQUENCE
MAX1997 toc12
4ms/div
B
A
C
0
10V
-10V
0
10V
20V
0
A: V
MAIN
, 10V/div
B: V
SOURCE
, 10V/div
C: V
GATE_ON
, 10V/div
D: V
GATE_OFF
, 10V/div
V
ONN
< V
ONP
< V
ON2
D
10V
0
POWER-UP SEQUENCE
MAX1997 toc13
4ms/div
B
A
C
0
10V
-10V
0
10V
20V
0
A: V
MAIN
, 10V/div
B: V
SOURCE
, 10V/div
C: V
GATE_ON
, 10V/div
D: V
GATE_OFF
, 10V/div
V
ONN
> V
ONP
> V
ON2
D
10V
0