Rainbow Electronics MAX1531 - Manual (Page 7)

MAX1530/MAX1531
Multiple-Output Power-Supply Controllers for
LCD Monitors
_______________________________________________________________________________________ 7
Typical Operating Characteristics
(Circuit of Figure 1; including R5, R6, and D2; T A = +25°C, unless otherwise noted.)
STEP-DOWN EFFICIENCY vs. LOAD CURRENT
MAX1530 toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
1200 900 600 300
60
70
80
90
100
50
0 1500
V IN = 12V
V
IN
= 20V
f SW = 500kHz
STEP-DOWN LOAD REGULATION
MAX1530 toc02
LOAD CURRENT (mA)
OUTPUT-VOLTAGE ERROR (%)
1200 900 600 300
-0.12
-0.08
-0.04
0
-0.16
0 1500
SWITCHING FREQUENCY vs. LOAD CURRENT
FREQUENCY (kHz)
485
490
495
500
510
505
515
520
480
MAX1530 toc03
LOAD CURRENT (mA)
1200 900 600 300 0 1500
STEP-DOWN REGULATOR LOAD TRANSIENT
MAX1530 toc04
40 µs/div
A: LOAD CURRENT, 1A/div
B: OUTPUT VOLTAGE, 200mV/div, AC-COUPLED
C: INDUCTOR CURRENT, 1A/div
A
0A
B
3.3V
0A
C
STEP-DOWN REGULATOR
SWITCHING WAVEFORM
MAX1530 toc05
2 µs/div
A
B
C
A: LX, 10V/div
B: OUTPUT VOLTAGE, 20 mV/div, AC-COUPLED
C: INDUCTOR CURRENT, 1A/div
0V
3.3V
0A
STEP-DOWN REGULATOR
SOFT-START
MAX1530 toc06
1ms/div
A
C
A: EN, 2V/div
B: OUTPUT VOLTAGE, 2V/div
C: INDUCTOR CURRENT, 1A/div
0V
0V
B
0A
VL LOAD REGULATION
MAX1530 toc07
LOAD CURRENT (mA)
VL OUTPUT ERROR (%)
25 20 15 10 5
-0.4
-0.3
-0.2
-0.1
0
-0.5
0 30
STARTUP SEQUENCE
MAX1530 toc08
4ms/div
A: V L , 10V/div
B: V
OUT
, 5V/div
C: V LOGIC , 5V/div
D: V SOURCE , 20V/div
E: V GAMMA , 20V/div
F: V
GOFF
, 20V/div
G: V GON , 40V/div
A
B
C
D
E
F
G
LR1 BASE CURRENT
vs. DRV1 VOLTAGE
MAX1530 toc09
DRV1 VOLTAGE (V)
BASE CURRENT (mA)
8 6 4 2
3
6
9
12
15
0
0 10
V FBL1 = 1.175V