Datasheet

MAX1856
Wide Input Range, Synchronizable,
PWM SLIC Power Supply
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
CC
= V
SYNC/SHDN
= 12V, V
OUT1
= -24V, V
OUT2
= -72V, R
OSC
= 200kΩ, unless otherwise noted.)
1.240
1.250
1.245
1.255
1.260
REFERENCE VOLTAGE
vs. REFERENCE CURRENT
MAX1856 toc16
REFERENCE CURRENT (µA)
V
REF
(V)
0 200100 300 500
400
1.240
1.250
1.245
1.255
1.260
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX1856 toc17
TEMPERATURE (°C)
V
REF
(V)
-40 10-15 35 85
60
NO LOAD
1000
100
100 1000
SWITCHING FREQUENCY vs. R
OSC
MAX1856 toc18
R
OSC
(kΩ)
SWITCHING FREQUENCY (kHz)
0
200
100
400
300
500
600
-40 10-15 35 60 85
SWITCHING FREQUENCY
vs. TEMPERATURE
MAX1856 toc19
TEMPERATURE (°C)
SWITCHING FREQUENCY (kHz)
R
OSC
= 100kΩ
R
OSC
= 200kΩ
R
OSC
= 500kΩ
70
0
0.1 1 10
EXT RISE/FALL TIME
vs. CAPACITANCE
10
MAX1856 toc20
CAPACITANCE (nF)
EXT RISE/FALL TIME (ns)
30
50
60
40
20
t
RISE
, V
IN
= 5V
t
RISE
, V
IN
= 3.3V
t
FALL
, V
IN
= 5V
t
FALL
, V
IN
= 3.3V
150
190
270
230
310
350
-40 10-15 35 60 85
SUPPLY CURRENT
vs. TEMPERATURE
MAX1856 toc13
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
R
OSC
= 100kΩ
R
OSC
= 200kΩ
R
OSC
= 500kΩ
CURRENT INTO V
CC
PIN
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0105 15202530
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
MAX1856 toc14
INPUT VOLTAGE (V)
SHUTDOWN CURRENT (µA)
CURRENT INTO V
CC
PIN
R
OSC
= 500kΩ
SYNC/SHDN = GND
0
50
150
100
200
250
0426810
LDO DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX1856 toc15
I
LDO
(mA)
DROPOUT VOLTAGE (V)
V
IN
= 5V
V
IN
= 3.3V