MAX5061 Maxim Integrated Products, MAX5061 Datasheet - Page 21

• Manufacturer Part Number: MAX5061
• Description: (MAX5060 / MAX5061) Average-Current-Mode DC-DC Controllers
• Manufacturer: Maxim Integrated Products

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).
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
10k
less than or equal to V
The VEA output is clamped to 930mV with respect to the
common-mode voltage (V
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
26.9mV/R
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
pin to ground, the hiccup current limit is set at 90% of
the full-load average current limit. Use R
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.
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
CLAMP(EA)
pullup resistor from PGOOD to a voltage source
S
.
Overvoltage Protection (OVP) (MAX5060)
. With no resistor connected from the LIM
Average-Current-Mode DC-DC Controllers
______________________________________________________________________________________
CC
PGOOD Generator (MAX5060)
.
CM
). Average current-mode
0.6V to 5.5V Output, Parallelable,
EXT
Current Limit
Protection
to increase
LIMIT
=
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
Connect OVI to the center tap of a resistor-divider from
V
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.
Figure 8. PGOOD Generator
Figure 9. Overvoltage Protection Input Delay
OUT
to SGND. In this case, the center tap is compared
DIFF
MAX5060
0.9 x V
V
CM
EAOUT
DIFF
EAN
OVI
REF
MAX5060
R
R
A
F
OUT
PGOOD
R
to SGND.
IN
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