Multi-Output, Low-Noise Power-Supply
Controllers for Notebook Computers
MAX1630–MAX1635
____________________________________Typical Operating Characteristics (continued)
(Circuit of Figure 1, 3A Table 1 components, T
A
= +25°C, unless otherwise noted.)
SWITCHING FREQUENCY
vs. LOAD CURRENT
MAX1630/35-10
VL REGULATOR OUTPUT VOLTAGE
vs. OUTPUT CURRENT
MAX 1630/35-11
1000
5.00
SWITCHING FREQUENCY (kHz)
+5V, V
IN
= 15V
10
+3.3V, V
IN
= 15V
VL OUTPUT VOLTAGE (V)
100
4.98
4.96
4.94
1
+3.3V, V
IN
= 6V
+5V, V
IN
= 6V
4.92
V
IN
= 15V
ON3 = ON5 = 0V
4.90
0.1
0.1
1
10
100
1000
LOAD CURRENT (mA)
0
10
20
30
40
50
60
OUTPUT CURRENT (mA)
REF OUTPUT VOLTAGE
vs. OUTPUT CURRENT
MAX 1630/35-12
START-UP WAVEFORMS
MAX1630/35-13
2.510
2.505
REF OUTPUT VOLTAGE (V)
2.500
2.495
2.490
2.485
2.480
0
1
2
3
4
5
6
OUTPUT CURRENT (mA)
V
IN
= 15V
ON3 = ON5 = 0V
RUN
5V/div
3.3V OUTPUT
2V/div
TIME
5V/div
5V OUTPUT
5V/div
2ms/div
SEQ = VL, 0.015μF CAPACITOR ON-TIME
__________________________________________________________________________Pin Description
PIN
1
2
3
NAME
CSH3
CSL3
FB3
FUNCTION
Current-Sense Input for the 3.3V SMPS. Current-limit level is 100mV referred to CSL3.
Current-Sense Input. Also serves as the feedback input in fixed-output mode.
Feedback Input for the 3.3V SMPS; regulates at FB3 = REF (approx. 2.5V) in adjustable mode. FB3 is a
Dual Mode input that also selects the 3.3V fixed output voltage setting when tied to GND. Connect FB3
to a resistor divider for adjustable-output mode.
12V/120mA Linear Regulator Output. Input supply comes from V
DD
. Bypass 12OUT to GND with
1µF minimum.
Logic-Control Input for secondary feedback. Selects the PWM that uses a transformer and secondary
feedback signal (SECFB):
STEER = GND: 3.3V SMPS uses transformer
STEER = VL: 5V SMPS uses transformer
12OUT
(MAX1630/
32/33/35)
4
STEER
(MAX1631/
MAX1634)
6
_______________________________________________________________________________________
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
