MAX8535EUA+T Maxim Integrated Products, MAX8535EUA+T Datasheet - Page 13

• Manufacturer Part Number: MAX8535EUA+T
• Description: IC CNTRLR ORING MOSFET 8-MSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX8535EUA+T

• Applications: Network/Telecom Power Supplies, Rectifiers
• Fet Type: N-Channel
• Number Of Outputs: 1
• Internal Switch(s): No
• Delay Time - Off: 200ns
• Voltage - Supply: 8 V ~ 14 V
• Current - Supply: 2mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Delay Time - On: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

for the MAX8536 is 12µA. Increasing the charge-pump
frequency increases the GATE drive current. Adding a
resistor from GATE to the gate of the external MOSFETs
further increases turn-on and turn-off times.
The voltage drop across the external MOSFETs is mea-
sured between the V
the positive side of the system bus. The voltage drop
across the CS and V
I
defined as CS - V
MAX8585. In the MAX8585, I
The MAX8535/MAX8536/MAX8585 contain a versatile
FAULT output that signals overvoltage, undervoltage,
or reverse-current conditions. During a FAULT condi-
tion, the charge pump shuts down and the GATE dis-
charges to ground.
The MAX8535/MAX8536/MAX8585 turn off the external
MOSFET if the input voltage falls below the UVP thresh-
old. If UVP is left unconnected, the undervoltage input
is disabled. Set the undervoltage threshold to any value
above V
UVP threshold, FAULT clears and the MOSFET turns
back on.
The MAX8535/MAX8536/MAX8585 contain an
adjustable OVP feature. A resistor-divider from the CS
system bus to the OVP input pin sets the overvoltage
threshold. When the OVP level is exceeded and the
part is in the I
CS + 0.01V), the MAX8535/MAX8536/MAX8585 turn off
the external MOSFET and a fault is latched. If there is
no I
Table 1. MAX8535/MAX8536/MAX8585 Fault Modes
FORWARD
V
UVP pin undervoltage protection
OVP pin overvoltage protection
Reverse-current protection
( M AX 8535/M AX 8536)
Reverse-current protection
( M AX 8585)
V
over vol tag e p r otecti on
CC
C C
FORWARD
UVLO
i nter nal ( M AX 8535/M AX 8585)
CCOK
FAULT MODE
Fault Isolation for Redundant Power Supplies
is defined as V
. When the input voltage rises above the
FORWARD
condition, an OVP detection has no
______________________________________________________________________________________
CC
CC
CC
ORing MOSFET Controllers with Fastest
and CS inputs. CS connects to
determines operation modes.
> 0.03V in all except the
condition (defined as V
CC
REVERSE
- CS > 0.01V. I
FAULT Conditions
Undervoltage Fault
Overvoltage Fault
= 0V.
Gate ON for t > 0.032s
Gate ON for t > 0.5s
PIN CONDITIONS
V
V
CC
CC
V
UVP < 1.25V
OVP > 1.25V
V
CC
V
CC
> CS + 0.01V
< CS - 0.03V
CC
REVERSE
< V
> 14.5V
< CS
CCOK
CC
CS
is
>
effect. In this way, only the input supply, which is caus-
ing the overvoltage condition, is turned off in a redun-
dant power system application. An overvoltage fault is
a latching fault condition, and requires V
to be cycled to reset the part.
The MAX8535/MAX8536 contain a reverse-current pro-
tection feature. If, after the 500ms (typ) startup blank
time, an I
MAX8536 turn off the external MOSFET and a fault is
latched. A reverse-current fault forces the MAX8535/
MAX8536 to latch off. Cycle V
latched fault condition. Startup blanking time allows the
incoming power supply to connect to the system bus at
V
increases the startup blanking time. The MAX8585
does not latch this fault.
To set the frequency of the internal charge-pump oper-
ation, connect a resistor from TIMER to GND.
Determine the frequency by using the equation:
Pull TIMER above 1.5V for maximum charge-pump fre-
quency. Pull TIMER below 0.5V to disable the charge
pump. Leave TIMER unconnected for a 500kHz
charge-pump frequency.
The charge pump uses an internal monolithic transfer
capacitor to charge the external MOSFET gates.
BUS
Frequency
- 0.4V. Reducing charge-pump frequency
GATE PIN
REVERSE
Low
Low
Low
Low
Low
Low
Applications Information
Selecting the Gate Capacitor
5
Selecting the Timer Resistor
condition is detected, the MAX8535/
High impedance
100
FAULT PIN
A
Low
Low
Low
Low
Low
-
R
Reverse-Current Fault
1 25
CC
and Gate Resistor
TIMER
.
or TIMER to exit a
V
kHz
LATCHING
CC
/
Yes
Yes
No
No
No
No
or TIMER
A
13