MAX8792 Maxim Integrated Products, MAX8792 Datasheet - Page 18

• Manufacturer Part Number: MAX8792
• Description: Single Quick-PWM Step-Down Controller
• Manufacturer: Maxim Integrated Products

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Single Quick-PWM Step-Down
Controller with Dynamic REFIN
Figure 5. Power-Good and Fault Protection
voltage, connect an external pullup resistor between
PGOOD and V
most applications. Figure 5 shows the power-good and
fault-protection circuitry.
When the internal feedback voltage rises 300mV above
the target voltage and OVP is enabled, the OVP compara-
tor immediately pulls DH low and forces DL high, pulls
PGOOD low, sets the fault latch, and disables the SMPS
controller. Toggle EN or cycle V
POR to clear the fault latch and restart the controller.
When the feedback voltage drops 200mV below the
target voltage (REFIN), the controller immediately pulls
PGOOD low and triggers a 200µs one-shot timer. If the
feedback voltage remains below the undervoltage fault
threshold for the entire 200µs, then the undervoltage
fault latch is set and the SMPS begins the shutdown
sequence. When the internal target voltage drops
below 0.1V, the MAX8792 forces DL low. Toggle EN or
cycle V
and restart the controller.
18
______________________________________________________________________________________
CC
SOFT-START
power below V
COMPLETE
POWER-GOOD AND FAULT PROTECTION
DD
EN
. A 100kΩ pullup resistor works well in
Undervoltage Protection (UVP)
Overvoltage Protection (OVP)
CC
POR to clear the fault latch
CC
power below the V
200μs
SHOT
ONE-
IN
CLK
OUT
- 200mV
TARGET
CC
The MAX8792 features a thermal fault-protection circuit.
When the junction temperature rises above +160°C, a
thermal sensor activates the fault latch, pulls PGOOD
low, and shuts down the controller. Both DL and DH are
pulled low. Toggle EN or cycle V
POR to reactivate the controller after the junction tem-
perature cools by 15°C.
The DH and DL drivers are optimized for driving mode-
rate-sized high-side and larger low-side power
MOSFETs. This is consistent with the low duty factor
seen in notebook applications, where a large V
V
sources and sinks 1.5A, and the low-side gate driver
(DL) sources 1.0A and sinks 2.4A. This ensures robust
gate drive for high-current applications. The DH floating
high-side MOSFET driver is powered by internal boost
switch charge pumps at BST, while the DL synchro-
nous-rectifier driver is powered directly by the 5V bias
supply (V
OUT
differential exists. The high-side gate driver (DH)
OVP
DD
+ 300mV
TARGET
).
Thermal-Fault Protection (TSHDN)
FAULT
LATCH
MOSFET Gate Drivers
FB
OVP ENABLED
CC
POWER-GOOD
FAULT
power below V
IN
CC
-