MAX1816 Datasheet, PDF (36/49 Pages) Maxim Integrated Products – Dual Step-Down Controllers Plus Linear- Regulator Controller for Notebook Computers

Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
Table 7. Offset Selection Truth Table
MODE
Battery Sleep
Battery
Performance Sleep
Performance
Suspend
Suspend
Suspend
Suspend
SUS
0
0
0
0
1
1
1
1
0 = Logic low or input not selected.
1 = Logic high or input selected.
INPUTS
PERF
0
0
1
1
0
0
1
1
DPSLP
0
1
0
1
0
1
0
1
OFS2
1
0
0
0
0
0
0
0
ACTIVE OFS INPUTS
OFS1
0
1
0
0
0
0
0
0
OFS0
0
0
1
0
0
0
0
0
Output Overvoltage Protection
Output overvoltage protection (OVP) is available on
BUCK1, BUCK2, and the linear regulator. The LINFB
input is always monitored for overvoltage. The FBS and
OUT2 inputs are only monitored for overvoltages when
OVP is enabled. When any output exceeds the desired
OVP threshold, the fault latch is set and the regulator is
turned off. In the fault mode, DL1 and DL2 are forced
high, DH1 and DH2 are forced low, and the linear regu-
lator is turned off. For BUCK1 and BUCK2, if the condi-
tion that caused the overvoltage (such as a shorted
high-side MOSFET) persists, the battery fuse will blow.
DL1 is also kept high continuously when V_CC UVLO is
active, as well as in shutdown mode (Table 4). The
device remains in the fault mode until V_CC is cycled, or
either SKP_/SDN or LIN/SDN is toggled. The triggering
of the reset condition occurs on the rising edge of the
SKP_/SDN or LIN/SDN signals.
For BUCK1, the default OVP threshold is 2V for the
MAX1816 and 2.25V for the MAX1994. For BUCK2, the
OVP threshold is 115% of the nominal voltage for OUT2
(FB2 if external feedback is used for BUCK2). The over-
voltage detection level for FBS can be adjusted through
an external resistive voltage-divider. Connecting OVPSET
to a voltage between 1.0V and 2.0V sets the OVP thresh-
old for FBS. For the MAX1816, the fault latch is set when
V_FBS > V_OVPSET. For the MAX1994, the fault latch is set
when V_FBS > 1.125 ✕ V_OVPSET. The OVP threshold on
OUT2 is not adjustable and remains at the default value
of 115%. Connecting OVPSET to V_CC disables OVP for
BUCK1 and BUCK2. The operation of the linear regulator
is not affected by OVPSET. Overvoltage protection can
be disabled using the NO FAULT test mode (see the NO
FAULT Test Mode section).
DH2
MAX1816
MAX1994 _DL2
CS2
OUT2
FB2
PGND
AGND
V_BATT
V_OUT
R1
R2
Figure 11. Adjusting BUCK2 Output Voltage with a Resistive
Voltage-Divider
Output Undervoltage Protection
The output undervoltage protection (UVP) is available on
BUCK1, BUCK2, and the linear regulator. The protection
is similar to foldback current limiting, but employs a timer
rather than a variable current limit. If the output voltage is
under 70% of the nominal value for BUCK1 and BUCK2,
and under 90% for the linear regulator (see the Electrical
Characteristics table for the respective UVP thresholds),
the fault latch is set. In the fault mode, DL1 and DL2 are
forced high, DH1 and DH2 are forced low, and the linear
regulator is turned off. The controller does not restart until
V_CC power is cycled, or either SKP_/SDN or LIN/SDN is
toggled. The triggering of the reset condition occurs on
the rising edge of the SKP_/SDN or LIN/SDN signals.
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