MAX16047_09 Datasheet, PDF (54/61 Pages) Maxim Integrated Products – 12-Channel/8-Channel EEPROM-Programmable System Managers with Nonvolatile Fault Registers

12-Channel/8-Channel EEPROM-Programmable
System Managers with Nonvolatile Fault Registers
V_IN
V_CC
C
MAX16047
MAX16049
If more than six series-pass MOSFETs are required for
an application, additional series-pass p-channel
MOSFETS may be connected to outputs configured as
active-low open drain (Figure 17). Connect a pullup
resistor from the gate to the source of the MOSFET, and
ensure the absolute maximum ratings of the
MAX16047/MAX16049 are not exceeded.
V_IN
V_OUT
GND
Figure 15. Power Circuit for Shutdown During Fault Conditions
Driving High-Side MOSFET Switches
The MAX16047/MAX16049 use external n-channel
MOSFET switches for voltage tracking applications. To
configure the part for closed-loop voltage tracking using
series-pass MOSFETs, configure up to four of the pro-
grammable outputs (EN_OUT1–EN_OUT4) of the
MAX16047/MAX16049 as closed-loop tracking outputs
and configure up to four of the GPIOs as sense-return
inputs (INS1–INS4). Connect the EN_OUT_ output to the
gate of an n-channel MOSFET, connect the source of the
MOSFET to the INS_ feedback input, and monitor the
drain side of the MOSFET with the corresponding MON_
input (see Figure 16). Both the input and the output must
be assigned to the same slot (see the Closed–Loop
Tracking section). Configure the power-up and power-
down slew rates in the configuration registers. To provide
additional control over power-down, enable the internal
100Ω pulldown resistors on the INS_ connections.
Up to six of the programmable outputs (EN_OUT1–
EN_OUT6) of the MAX16047/MAX16049 may be config-
ured as charge-pump outputs. In this case, they can
drive the gates of series-pass n-channel MOSFETS with-
out closed-loop tracking functionality. When configured
in this way, these outputs act as simple power switches
to turn on the voltage supply rails. Approximate the slew
rate, SR, using the following formula:
( ) ^{SR =}
I_CP
C_GATE + C_EXT
MON_
ADC MUX
LOGIC
REFERENCE
RAMP
EN_OUT_ INS_
GATE
DRIVE
V_{TH_PG}
100Ω
Figure 16. Closed-Loop Tracking
V_IN
S
D
V_OUT
R
G
MON_
EN_OUT_
MAX16047
MAX16049
where I_CP is the 6µA (typ) charge-pump source cur-
rent, C_GATE is the gate capacitance of the MOSFET,
and C_EXT is the capacitance connected from the gate
to ground. Power-down is not well controlled due to the
absence of the 100Ω pulldowns.
Figure 17. Connection for a p-Channel Series-Pass MOSFET
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