Owner manual

MAX8728
Low-Cost, Multiple-Output
Power Supply for LCD Monitors/TVs
_______________________________________________________________________________________ 7
Note 1: When the inductor is in continuous conduction (EN = V
CC
or heavy load), the output voltage has a DC regulation level lower
than the error comparator threshold by 50% of the output voltage ripple. In discontinuous conduction (EN = GND with light
load), the output voltage has a DC regulation level higher than the error comparator threshold by up to 50% of the output
voltage ripple.
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
IN
= V
INL
= V
SUPP
= 12V, V
OUT1
= +3.3V, V
SRC
= 28V, GND1 = GND2 = GNDP = GND = 0, I
REF
= 0, T
A
=
-40°C to +85°C.) (Note 2)
PARAMETER CONDITIONS MIN TYP MAX
UNITS
CHARGE-PUMP REGULATORS
FBP Regulation Voltage 1.97 2.02 V
FBN Regulation Voltage V
REF
- V
FBN
1.71 1.78 V
SEQUENCE CONTROL
SHDN Input Low Voltage 0.4 V
SHDN Input High Voltage 2 V
EN Turn-On Threshold 0.95 1.10 V
DEL Turn-On Threshold 0.95 1.10 V
GATE On Voltage EN = high
V
IN
- 6
V
IN
- 4 V
GATE Done Threshold EN = high, V
GATE
_
DONE
- V
GATE
_
ON
0V
POSITIVE GATE-DRIVER TIMING AND CONTROL SWITCHES
CTL Input Low Voltage 0.6 V
CTL Input High Voltage 2.1 V
SRC Input Voltage Range 38 V
V
MODE
= V
REF
, V
DEL
= V
CTL
= 3V 2.3
SRC Input Current
V
MODE
= V
REF
, V
DEL
= 3V, V
CTL
= 0 0.2
mA
SRC Switch On-Resistance V
MODE
= V
REF
, V
DEL
= V
CTL
= 3V 30 Ω
DRN Switch On-Resistance
V
MODE
= V
REF
, V
DEL
= 3V, V
CTL
= 0,
V
GON
= 28V, V
THR
= 1.4V
50 Ω
MODE Current-Source Stop-
Voltage Threshold
MODE rising 1.2 1.6 V
MODE Voltage Threshold Enabling DRN switch control in mode 2 0.8 1.2 V
THR-to-GON Voltage Gain 9.4 10.6 V/V