MAX1533 Datasheet, PDF (25/38 Pages) Maxim Integrated Products – High-Efficiency, 5x Output, Main Power-Supply Controllers for Notebook Computers

High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
LDO5
MAX1533
MAX1537
BST
DH
LX
LDO5
DL
GND
(R_BST)*
C_BST
(C_NL)*
C_BYP
D_BST
INPUT (V_IN)
N_H
L
N_L
(R_BST)* OPTIONAL—THE RESISTOR LOWERS EMI BY DECREASING
THE SWITCHING-NODE RISE TIME.
(C_NL)* OPTIONAL—THE CAPACITOR REDUCES LX TO DL CAPACITIVE
COUPLING THAT CAN CAUSE SHOOT-THROUGH CURRENTS.
Figure 6. Optional Gate-Driver Circuitry
Power-Good Output (PGOOD)
PGOOD is the open-drain output of a comparator that
continuously monitors both SMPS output voltages for
undervoltage conditions. PGOOD is actively held low in
shutdown (SHDN or ON3 or ON5 = GND), soft-start,
and soft-shutdown. Once the digital soft-start termi-
nates, PGOOD becomes high impedance as long as
both outputs are above 90% of the nominal regulation
voltage set by FB_. PGOOD goes low once either
SMPS output drops 10% below its nominal regulation
point, an output overvoltage fault occurs, or either
SMPS controller is shut down. For a logic-level PGOOD
output voltage, connect an external pullup resistor
between PGOOD and V_CC. A 100kΩ pullup resistor
works well in most applications.
PGOOD is independent of the fault protection states
OVP and UVP.
Fault Protection
Output Overvoltage Protection (OVP)
If the output voltage of either SMPS rises above 111%
of its nominal regulation voltage and the OVP protection
is enabled (OVP = GND), the controller sets the fault
latch, pulls PGOOD low, shuts down both SMPS con-
trollers, and immediately pulls DH_ low and forces DL_
POWER-GOOD
0.9 x
INT REF_
FAULT
PROTECTION
0.7 x
INT REF_
1.11 x
INT REF_
INTERNAL FB
TIMER
POR
FAULT
LATCH
ENABLE OVP
ENABLE UVP
BLANK
(POWER-UP)
FAULT
POWER-
GOOD
Figure 7. Power-Good and Fault Protection
______________________________________________________________________________________ 25