Datasheet

MAX5060/MAX5061
0.6V to 5.5V Output, Parallelable,
Average-Current-Mode DC-DC Controllers
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Protection
The MAX5060 includes a power-good generator
(PGOOD) for undervoltage protection (UVP), and a
reverse current-limit protection; the MAX5060/MAX5061
include a hiccup current-limit protection to prevent dam-
age to the powered electronic circuits. Additionally, the
MAX5060 includes output overvoltage protection (OVP).
PGOOD Generator (MAX5060)
A PGOOD comparator compares the differential ampli-
fier output (DIFF) against 0.90 times the set output volt-
age for undervoltage monitoring (see Figure 8). Use a
10kΩ pullup resistor from PGOOD to a voltage source
less than or equal to V
CC
.
Current Limit
The VEA output is clamped to 930mV with respect to the
common-mode voltage (V
CM
). Average current-mode
control has the ability to limit the average current sourced
by the converter during a fault condition. When a fault
condition occurs, the VEA output clamps to 930mV with
respect to the common-mode voltage (0.6V) to limit the
maximum current sourced by the converter to I
LIMIT
=
26.9mV/R
S
.
The hiccup current limit overrides the average current
limit. The MAX5060/MAX5061 include hiccup current-
limit protection to reduce the power dissipation during
a fault condition. The hiccup current-limit circuit derives
inductor current information from the output of the cur-
rent amplifier. This signal is compared against one half
of V
CLAMP(EA)
. With no resistor connected from the LIM
pin to ground, the hiccup current limit is set at 90% of
the full-load average current limit. Use R
EXT
to increase
the hiccup current limit from 90% to 100% of the full-
load average limit (see Figures 1 and 2). The hiccup
current limit can be disabled by connecting LIM to
SGND. In this case, the circuit will follow the average
current-limit action during overload conditions.
An internal clamp (MAX5060) limits the continuous
reverse current the buck converter sinks when a higher
voltage is applied at the output. The reverse current limit
translated at the current-amplifier input is -2.3mV (typ).
The maximum reverse current the converter sinks
depends on the current-sense resistor. Normally it is
about 10% of the full load current.
Overvoltage Protection (OVP) (MAX5060)
The OVP comparator compares the OVI input to the over-
voltage threshold. The overvoltage threshold is typically
+12.7% above the internal 0.6V reference voltage. A
detected overvoltage event latches the comparator output
forcing the power stage into the OVP state. In the OVP
state, the high-side MOSFET turns off and the low-side
MOSFET latches on. Connect DIFF to OVI for differential
output sensing and overvoltage protection. Alternately,
use a separate sensing network from V
OUT
to SGND.
Connect OVI to the center tap of a resistor-divider from
V
OUT
to SGND. In this case, the center tap is compared
against 1.276V. Add an RC delay to reduce the sensitivity
of the overvoltage circuit and avoid nuisance tripping of
the converter (Figure 9). Disable the overvoltage function
by connecting OVI to SGND.
V
CM
0.9 x V
REF
PGOOD
DIFF
MAX5060
Figure 8. PGOOD Generator
R
A
OVI
DIFF
MAX5060
EAN
R
F
R
IN
EAOUT
Figure 9. Overvoltage Protection Input Delay