Datasheet
A. V
OUT
= -48V, I
OUT
= 200mA, 50mV/div
B. I
LP
, 2A/div
CIRCUIT OF FIGURE 4
HEAVY-LOAD SWITCHING WAVEFORM
MAX1856 toc23
-47.2V
-47.0V
-47.1V
2A
0
2.0µs/div
A
B
4A
A. V
OUT
= -48V, I
OUT
= 20mA, 20mV/div
B. I
LP
, 2A/div
CIRCUIT OF FIGURE 4
LIGHT-LOAD SWITCHING WAVEFORM
MAX1856 toc24
-47.80V
-47.72V
-47.76V
2A
0
4µs/div
A
B
MAX1856
Wide Input Range, Synchronizable,
PWM SLIC Power Supply
_______________________________________________________________________________________ 7
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.)
A. I
OUT
= 20mA TO 200mA, 200mA/div
B. V
OUT
, = -48V, 500mV/div
C. I
LP
, 2A/div
CIRCUIT OF FIGURE 4
LOAD TRANSIENT
MAX1856 toc25
-47.6V
0
1ms/div
A
B
200mA
-47.1V
-48.1V
C
-100
-60
-80
-20
-40
20
0
60
40
0 50 100 150 200 250
RINGER TO TALK-BATTERY CROSSTALK
MAX1856 toc27
FREQUENCY (Hz)
(dB)
TALK-BATTERY OUTPUT
RINGER OUTPUT
A. V
IN
= 10V TO 14V, 2Vdiv
B. V
OUT
= -48V, I
OUT
= 200mA, 100mV/div
CIRCUIT OF FIGURE 4
LINE TRANSIENT
MAX1856 toc26
14V
10V
400µs/div
A
B
12V
-47V
A. V
SYNC
/
SHDN
= 0 TO 5V, 5V/div
B. I
LP
, 2A/div
C. V
OUT
= -48V, R
OUT
= 2.4kΩ, 20V/div
CIRCUIT OF FIGURE 4
EXITING SHUTDOWN
MAX1856 toc21
-60V
0
5V
0
2A
0
-20V
-40V
4ms/div
A
B
C
A. V
SYNC
/
SHDN
= 5V TO 0, 5V/div
B. V
EXT
, 5V/div
C. I
LP
, 2A/div
V
OUT
= -48V, R
OUT
= 240Ω
CIRCUIT OF FIGURE 4
ENTERING SHUTDOWN
MAX1856 toc22
0
5V
0
5V
2A
0
10µs/div
A
B
C