MAX6765–MAX6774
Automotive Micropower Linear Regulators
with Supervisor
15
Maxim Integrated
Regulator
The regulator accepts an input voltage from +4V to +72V.
All of the devices feature fixed output-voltage options of
+1.8V, +2.5V, +3.3V, and +5V. The MAX6767–MAX6774B
feature an adjustable output voltage set with an external
resistive-divider network connected between OUT, SET,
and GND. See Figure 1.
Enable and Hold Inputs
(MAX6767/MAX6768)
The MAX6767/MAX6768 support two logic inputs,
ENABLE (active-high) and HOLD (active-low), making
these devices “automotive friendly.” For example, when
the ignition key signal drives ENABLE high, the regulator
turns on and remains on even if ENABLE goes low, as
long as HOLD is forced low and kept low before
ENABLE goes low. In this state, releasing HOLD turns
the regulator output (OUT) off. This feature makes it pos-
sible to implement a self-holding circuit without external
components. Forcing ENABLE low with HOLD high (or
unconnected) places the MAX6767/MAX6768 into shut-
down mode, drawing 3.3µA (typ) of supply current.
Table 3 shows the state of the regulator output with
respect to the voltage level at ENABLE and HOLD.
Connect HOLD to OUT or leave it unconnected to allow
the ENABLE input to act as a standard enable/shut-
down switch for the regulator output (OUT).
Reset Output
The reset output is typically connected to the reset
input of a µP. A µP’s reset input starts or restarts the µP
in a known state. The MAX6765–MAX6774B superviso-
ry circuits provide the reset logic to prevent code-exe-
cution errors during power-up, power-down, and
brownout conditions (see the
Typical Application
Circuit
). RESET changes from high to low whenever the
monitored voltage drops below the reset threshold volt-
ages. Once the monitored voltage exceeds its respec-
tive reset threshold voltage(s), RESET remains low for
the reset timeout period, then goes high. See Table 1
and Table 2.
RESETIN Threshold (MAX6769/MAX6770)
The MAX6769/MAX6770 monitor the voltage on RESETIN
using an adjustable reset threshold (V
RESETIN
) set with
an external resistive voltage-divider and the internal reset
threshold (V
TH
). See Table 2.
1.147
1.085
T 3.3 3.353
1.147
S 3.3 2.888
1.085
Z 2.5 2.313
1.147
Y 2.5 2.188
1.085
W 1.8 1.665
1.147
V 1.8 1.575
1.085
