MAX6397LATA+T Maxim Integrated Products, MAX6397LATA+T Datasheet - Page 8

• Manufacturer Part Number: MAX6397LATA+T
• Description: IC SW OVERVOLT PROT 8-TDFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX6397LATA+T

• Voltage - Working: 72V
• Technology: Mixed Technology
• Power (watts): 1.45W
• Number Of Circuits: 1
• Applications: General Purpose
• Package / Case: 8-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Clamping: -

The MAX6397 integrates a high-input-voltage, low-qui-
escent-current linear regulator in addition to an over-
voltage protector circuit. The linear regulator remains
enabled at all times to power low-current “always-on”
applications (independent of the state of the external
MOSFET). The regulator is offered with several stan-
dard output voltage options (5V, 3.3V, 2.5V, or 1.8V).
An open-drain power-good output notifies the system if
the regulator output falls to 92.5% or 87.5% of its nomi-
nal voltage. The MAX6397’s REG output operates inde-
pendently of the SHDN logic input.
The MAX6397/MAX6398 include internal thermal-shut-
down protection, disabling the external MOSFET and
linear regulator if the chip reaches overtemperature
conditions.
Overvoltage Protection Switch/Limiter
Controllers Operate Up to 72V
Figure 1. Functional Diagram
8
SET
_______________________________________________________________________________________
1.23V
5V
MAX6397
MAX6398
IN
UVLO
V
POK_TH
REGULATOR
LINEAR
MAX6397 ONLY
PROTECTION
THERMAL
10V
CHARGE
PUMP
GATE
OUT
SHDN
REG
POK
GND
The MAX6397 is available with 5.0V, 3.3V, 2.5V, and 1.8V
factory-set output voltages. Each regulator sources up to
100mA and includes a current limit of 230mA. The linear
regulator operates in an always-on condition regardless
of the SHDN logic. For fully specified operation, V
be greater than 6.5V for the MAX6397L/M (5V regulator
output). The actual output current may be limited by the
operating condition and package power dissipation.
POK is an open-drain output that goes low when REG
falls to 92.5% or 87.5% (see the Selector Guide ) of its
nominal output voltage. To obtain a logic-level output,
connect a pullup resistor from POK to REG or another
system voltage. Use a resistor in the 100kΩ range to
minimize current consumption. POK provides a valid
logic-output level down to V
The MAX6397/MAX6398 use a high-efficiency charge
pump to generate the GATE voltage. Upon V
ing the 5V (typ) UVLO threshold, GATE enhances 10V
above IN (for V
overvoltage condition occurs when the voltage at SET
pulls above its 1.215V threshold. When the threshold is
crossed, GATE falls to OUT within 100ns with a 100mA
(typ) pulldown current. The MAX6397/MAX6398 include
an internal clamp to OUT that ensures GATE is limited
to 18V (max) above OUT to prevent gate-to-source
damage to the external FET.
The GATE cycle during overvoltage limit and overvolt-
age switch modes are quite similar but have distinct
characteristics. In overvoltage switch mode (Figure 2a),
GATE is enhanced to V
voltage remains below the overvoltage fault threshold
(SET < 1.215V). When an overvoltage fault occurs (SET
≥ 1.215V), GATE is pulled one diode below OUT, turn-
ing off the external FET and disconnecting the load
from the input. GATE remains low (FET off) as long as
V
back below the overvoltage fault threshold (-5% hys-
teresis) GATE is again enhanced to V
In overvoltage limit mode (Figure 2b), GATE is enhanced
to V
below the overvoltage fault threshold (SET < 1.215V).
When an overvoltage fault occurs (SET ≥ 1.215V),
GATE is pulled low one diode drop below OUT until
OUT drops 5% below the overvoltage fault threshold.
GATE is then turned back on until OUT again reaches
the overvoltage fault threshold and GATE is again
turned off.
IN
is above the overvoltage fault threshold. As V
IN
+ 10V. While the monitored OUT voltage remains
Linear Regulator (MAX6397 Only)
IN
≥14V) with a 75µA pullup current. An
IN
+ 10V while the monitored IN
IN
= 1.5V.
Power-OK Output
IN
GATE Voltage
+ 10V.
IN
exceed-
IN
IN
must
falls