MAX783 Datasheet, PDF (9/28 Pages) Maxim Integrated Products – Triple-Output Power-Supply Controller for Notebook Computers

Triple-Output Power-Supply Controller
for Notebook Computers
BATTERY INPUT
5.5V TO 30V
C1
(NOTE 1)
33µF
29
28
C7
C2
+5V at 5mA _33µF
VPP
CONTROL
INPUTS
V+
16
DA0
15
DA1
18
DB0
VL
9
VPPA
11
VPPB
4.7µF
C8
1µF
C9
0V, 3.3V, 5V, 12V
0V, 3.3V, 5V, 12V
17
DB1
D1A
VDD ¹⁰
1µF
D1B
D3
EC11FS1
+15V AT 200mA, SEE
HIGH-SIDE SUPPLY (VDD)
SECTION.
MAX783
C11
D6
C10
0.1µF
R1
L1 N1
24
BST5
22
DH5
31
BST3
DH3 ³³
0.1µF
N3 ^1:4
C12
2.2µF
18V
100mW (NOTE 3)
+5V
25mΩ 10µH
at
23
LX5
32
LX3
3A
D2
25
DL5
DL3 ³⁰
1N5819
N2
21
35
L2 10µH
R2
N4
D5
1N5819
20mΩ
+3.3V
at
3A
CS5
CS3
C3 C4
330µF 330µF
+3.3V ON/OFF
(NOTE 2)
C13
0.01µF
27 _FB5
20 _SS5
1 _ON3
FB3 ³⁴
SS3 ³⁶
5
VH
(NOTE 2)
C14
0.01µF
C5 C6
150µF 150µF
COMPARATOR SUPPLY INPUT
+5V ON/OFF
19 _ON5
3, 4
D1-D2
2
COMPARATOR INPUTS
7, 6
Q1-Q2
2
COMPARATOR OUTPUTS
SHUTDOWN
2 _SHDN
SYNC ¹⁴
OSCILLATOR SYNC
5V POWERGOOD
8 _RDY5
REF ¹³
3.3V AT 5mA
C1–C6 = SPRAGUE 595D or AVX TPS SERIES
N1–N4 = Si9410DY or IRF7101 (BOTH SECTIONS)
PGND GND
C15
1µF
26
12
D1A, D1B = LOW-POWER SCHOTTKY (CMPSH3 OR EQUIVALENT)
FOR V+ < 6V. FOR V+ > 6V, 1N4148 OR EQUIVALENT IS ACCEPTABLE.
NOTE 1: BATTERY VOLTAGE RANGE 6V to 20V WITH COMPONENTS SHOWN.
NOTE 2: KEEP KELVIN-CONNECTED CURRENT-SENSE TRACES SHORT AND CLOSE TOGETHER. SEE FIG.5.
NOTE 3: ZENER DIODE CLAMP REQUIRED FOR VIN > 12V. ZENER CAN BE REPLACED WITH 20kΩ PULL-DOWN OR OTHER 1mA MINIMUM LOAD.
Figure 1. Standard Application Circuit
zero (in discontinuous mode). Under fault conditions
when the inductor current exceeds the 100mV current-
limit threshold, the high-side latch resets and the high-
side switch turns off.
At light loads, the inductor current fails to exceed the
25mV threshold set by the minimum current compara-
tor. When this occurs, the PWM goes into idle mode,
skipping most of the oscillator pulses in order to reduce
the switching frequency and cut back switching losses.
The oscillator is effectively gated off at light loads
because the minimum current comparator immediately
resets the high-side latch at the beginning of each
cycle, unless the FB_ signal falls below the reference
voltage level.
A flyback winding controller regulates the +15V VDD
supply in the absence of a load on the main 3.3V out-
put. If VDD falls below the preset +13V VDD regulation
threshold, a 1µs one-shot is triggered that extends the
low-side switch’s on-time beyond the point where the
inductor current crosses zero (in discontinuous mode).
This causes inductor (primary) current to reverse,
pulling current out of the output filter capacitor and
causing the flyback transformer to operate in the for-
ward mode. The low impedance presented by the
transformer secondary in forward mode allows the
+15V filter capacitor to be quickly charged up again,
bringing VDD into regulation.
_______________________________________________________________________________________ 9