MAX16049 Maxim Integrated Products, MAX16049 Datasheet - Page 54

• Manufacturer Part Number: MAX16049
• Description: (MAX16047 / MAX16049) 12-Channel/8-Channel EEPROM-Programmable System Managers
• Manufacturer: Maxim Integrated Products

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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:
where I
rent, C
and C
to ground. Power-down is not well controlled due to the
absence of the 100Ω pulldowns.
12-Channel/8-Channel EEPROM-Programmable
System Managers with Nonvolatile Fault Registers
Figure 15. Power Circuit for Shutdown During Fault Conditions
54
______________________________________________________________________________________
EXT
GATE
CP
Driving High-Side MOSFET Switches
is the capacitance connected from the gate
is the 6µA (typ) charge-pump source cur-
V
IN
is the gate capacitance of the MOSFET,
SR
C
=
(
C
GATE
V
I
CC
CP
+
MAX16047
MAX16049
C
EXT
GND
)
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.
Figure 16. Closed-Loop Tracking
Figure 17. Connection for a p-Channel Series-Pass MOSFET
REFERENCE
ADC MUX
LOGIC
RAMP
V
V
IN
IN
MON_
MON_
R
MAX16047
MAX16049
DRIVE
GATE
S
EN_OUT_
EN_OUT_
G
INS_
V
100Ω
TH_PG
D
V
OUT
V
OUT