1.8V to 28V Input, PWM Step-Up
Controllers in µMAX
MAX668/MAX669
Typical Operating Characteristics (continued)
(Circuits of Figures 2, 3, 4, and 5; T
A
= +25°C; unless otherwise noted.)
REFERENCE VOLTAGE vs.
TEMPERATURE
MAX668 toc10
SWITCHING FREQUENCY vs. R
OSC
450
SWITCHING FREQUENCY (kHz)
400
350
300
250
200
150
100
50
0
V
CC
= 5V
0
100
200
300
400
500
MAX668 toc11
1.250
1.249
REFERENCE VOLTAGE (V)
1.248
1.247
1.246
1.245
1.244
1.243
1.242
1.241
1.240
-40
-20
0
20
40
60
80
V
CC
= 5V
500
100
TEMPERATURE (°C)
R
OSC
(kΩ)
SWITCHING FREQUENCY vs.
TEMPERATURE
100kΩ
SWITCHING FREQUENCY (kHz)
500
400
165kΩ
300
200
499kΩ
100
V
IN
= 5V
0
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
0
100
10
MAX668 toc12
EXT RISE/FALL TIME vs.
CAPACITANCE
MAX668 toc13
600
60
50
EXT RISE/FALL TIME (ns)
t
R
, V
CC
= 3.3V
40
30
20
t
R
, V
CC
= 5V
t
F
, V
CC
= 5V
1000
CAPACITANCE (pF)
t
F
, V
CC
= 3.3V
10,000
6
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
