Typical operating characteristics – Rainbow Electronics MAX8758 User Manual
Page 6
MAX8758
Step-Up Regulator with Switch Control and
Operational Amplifier for TFT LCD
6
_______________________________________________________________________________________
Typical Operating Characteristics
(Circuit of
Figure
1, V
IN
= 3.3V, V
MAIN
= 8.5V, FREQ =
SHDN = IN, T
A
= +25°C, unless otherwise noted.)
STEP-UP REGULATOR EFFICIENCY
vs. LOAD CURRENT (V
MAIN
= 8.5V)
MAX8758 toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
100
10
55
60
65
70
75
80
85
90
95
50
1
1000
f
OSC
= 1.2MHz
L = 4.7µH
V
IN
= 5.5V
V
IN
= 1.8V
V
IN
= 3.3V
STEP-UP REGULATOR EFFICIENCY
vs. LOAD CURRENT (V
MAIN
= 8.5V)
MAX8758 toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
100
10
55
60
65
70
75
80
85
90
95
50
1
1000
f
OSC
= 640kHz
L = 10µH
V
IN
= 5.5V
V
IN
= 1.8V
V
IN
= 3.3V
OUTPUT VOLTAGE (V)
8.0
8.1
8.2
8.3
8.4
8.5
8.6
7.9
STEP-UP REGULATOR OUTPUT VOLTAGE
vs. LOAD CURRENT (V
MAIN
= 8.5V)
MAX8758 toc03
LOAD CURRENT (mA)
100
10
1
1000
f
OSC
= 1.2Hz
V
IN
= 3.3V
IN QUIESCENT CURRENT
vs. SUPPLY VOLTAGE
MAX8758 toc04
V
IN
(V)
SUPPLY CURRENT (
µ
A)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
10
20
30
40
50
0
1.5
5.5
CURRENT INTO IN PIN
NOT SWITCHING
V
FB
- 1.5V
TEMPERATURE (°C)
SUPPLY CURRENT (
µ
A)
60
35
10
-15
25
26
27
28
29
30
24
-40
85
IN QUIESCENT CURRENT
vs. TEMPERATURE
MAX8758 toc05
CURRENT INTO IN PIN
V
IN
= 3.3V
NOT SWITCHING
V
FB
- 1.5V
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
MAX8758 toc06
V
IN
(V)
SWITCHING FREQUENCY (kHz)
4.5
3.5
2.5
600
800
1000
1200
400
1.5
5.5
FREQ = V
IN
FREQ = AGND
I
MAIN
= 200mA
STEP-UP REGULATOR HEAVY-LOAD
SOFT-START
MAX8758 toc07
1ms
V
IN
2V/div
V
MAIN
5V/div
I
L
500mAV/div
STEP-UP REGULATOR LOAD TRANSIENT
RESPONSE
MAX8758 toc08
20µs/div
V
MAIN
AC-COUPLED
200mV/div
L = 4.7µH
R
COMP
= 100kΩ
C
COMP1
= 220pF
C
COMP2
= 47pF
50mA
0
I
MAIN
500mA/div
I
L
1AV/div