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TM
Data Sheet
ISL6436
August 2001
File Number 9023
USB Dual Port Power Supply Controller
The ISL6436 is a USB dual port power controller, fully
independent overcurrent (OC) fault protection IC.
Operational over the +2.5V to +5.5V range, this device
features internal current monitoring, accurate current
limiting, integrated power switches and current limited
delay to latch-off for system protection.
The ISL6436 current sense and limiting circuitry sets the
current limit to a nominal 1A, making this device well suited for
the USB port power management application. The ISL6436
provides OC fault notification, accurate current limiting and a
consistent timed latch-off thus isolating and protecting the
voltage bus in the presence of an OC event or short circuit. The
12ms time to latch-off is independent of the adjoining switch’s
electrical or thermal condition and the OC response time is
inversely related to the OC magnitude.
Each ISL6436 incorporates in a single 8 lead SOIC
package two 80mN-channel MOSFET power switches
for power control. Each switch is driven by a constant
current source giving a controlled ramp up of the output
voltage. This provides a soft start turn-on eliminating bus
voltage drooping caused by inrush current while charging
heavy load capacitances. Independent enabling inputs and
fault reporting outputs for each channel are compatible with
3V and 5V logic to allow external control and monitoring.
The ISL6436 undervoltage lockout feature prevents turn-on
of the outputs unless the correct ENABLE state and VIN >
2.5V are present. During initial turn-on the ISL6436
prevents fault reporting by blanking the fault signal. Rising
and falling outputs are current limited voltage ramps so that
both the inrush current and voltage slew rate are limited,
independent of load. This reduces supply droop due to
surge and eliminates the need for external EMI filters.
During operation, once an OC condition is detected the
appropriate output is current limited for 12ms to allow
transient conditions to pass. If still in current limit after the
current limit period has elapsed, the output is then latched
off and the fault is reported by pulling the corresponding
FAULT low. The FAULT signal is latched low until reset by
the ENABLE signal being de-asserted at which time the
FAULT signal will clear.
Features
• 80mIntegrated Power N-channel MOSFET Switches
• Accurate Current Sensing and 1A Current Limiting
• 12ms Fault Delay to Latch-Off, No Thermal Dependency
• 2.5V to 5.5V Operating Range
• Disabled Output Internally Pulled Low
• Undervoltage Lockout
• Controlled Turn-on Ramp Time
• Channel Independent Fault Output Signals
• Compatible with 3.3V and 5V Logic Families
• Channel Independent Logic Level Enable High Inputs
(ISL6436H) or Enable Low Inputs (ISL6436L)
Applications
• USB Port Power Management
• Electronic Circuit Limiting and Breaker
Ordering Information
PART NUMBER
ISL6436LIB
ISL6436LIB-T
TEMP.
RANGE
(oC)
PACKAGE
PKG. NO.
-40 to 85 8 Lead SOIC
M8.15
-40 to 85 8 Lead SOIC Tape and Reel
ISL6436HIB
-40 to 85 8 Lead SOIC
M8.15
ISL6436HIB-T
-40 to 85 8 Lead SOIC Tape and Reel
ISL6436EVAL1
Evaluation Platform
ISL6436USBEVAL1 USB Dual Port Evaluation Platform
Pinout
ISL6436 (SOIC)
TOP VIEW
GND 1
VIN 2
ENABLE_1 3
ENABLE_2 4
8 FAULT_1
7 OUT_1
6 OUT_2
5 FAULT_2
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143 | Intersil and Design is a trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2001, All Rights Reserved

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ISL6436
Typical Application: Dual USB Port Power
D+
D-
U
S OUT_1
B ENABLE_1
C FAULT_1
O
N +5V VIN
T GND
R ISL6436L
O
L FAULT_2
L
E
R ENABLE_2
OUT_2
D+
D-
Simplified Block Diagram
USB
PORT 1
V+
V+
USB
PORT_2
GND
CHANNEL 1 LIKE CHANNEL 2
FAULT_1
VIN
EN_1
EN_2
POR
Q-PUMP
CURRENT AND TEMP.
MONITORING, GATE AND
OUTPUT CONTROL
LOGIC
OUT_1
OUT_2
FAULT_2
2

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ISL6436
Pin Descriptions
PIN NO. DESIGNATOR
FUNCTION
DESCRIPTION
1
GND
IC Reference
2 VIN Chip bias, Controlled VIN provides chip bias voltage. At VIN < 2.5V chip functionality is disabled, FAULT latch
Supply Input,
is cleared and floating and OUT is held low.
Undervoltage lock-out
3, 4 ENABLE_1, 2 / Channel Enable /
Enables / Disables switch.
ENABLE_1,2 Enable Not Inputs
5, 8
FAULT_2, 1
Channel 2, 1 Over
Channel overcurrent fault indicator. FAULT floats and is disabled until VIN >2.5V. This
Current Fault Not
output is pulled low after the OC timeout period has expired and stays latched until
Indicator
ENABLE is deasserted.
6, 7
OUT_2, 1
Channel 2,1 Controlled Channel voltage output, connect to load to protect. Upon an OC condition IOUT is
Supply Output
current limited to 1A. Current limit response time is within 200µS. This output will remain
in current limit for a nominal 12ms before being latched off.
3

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ISL6436
Absolute Maximum Ratings
Supply Voltage (VIN to GND). . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0V
EN, FAULT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V
OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND -0.3V to VIN 0.3V
Output Current . . . . . . . . . . . . . . . . . . . . . . . Short Circuit Protected
ESD Rating
Human Body Model (Per MIL-STD-883 Method 3015.7) . . . . . 3kV
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to 85oC
Supply Voltage Range (Typical). . . . . . . . . . . . . . . . . . 2.7V to 5.5V
Thermal Information
Thermal Resistance (Typical, Note 1)
θJA (oC/W)
8 Lead SOIC Package . . . . . . . . . . . . . . . . . . . . . . .
116
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . 150oC
Maximum Storage Temperature Range . . . . . . . . . . -65oC to 150oC
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300oC
(SSOP - Lead Tips Only)
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE:
1. θJA is measured with the component mounted on a low effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
Electrical Specifications Supply Voltages = 5V, TA = TJ = -40 to 85oC, Unless Otherwise Specified
PARAMETER
SYMBOL
TEST CONDITIONS
POWER SWITCH
ISL6436 On Resistance at 2.7V
ISL6436 On Resistance at 3.3V
ISL6436 On Resistance at 5.0V
Disabled Output Voltage
Vout Rising Rate
Slow Vout Turn-off Rate
Fast Vout Turn-off Rate
CURRENT CONTROL
rDS(ON)_27
rDS(ON)_33
rDS(ON)_50
VOUT_DIS
t_vout_rt
t_svout_offt
t_fvout_offt
VIN = 2.7V, IOUT = 0.7A, TA = TJ = 25oC
TA = TJ = 85oC
VIN = 3.3V, IOUT = 0.7A, TA = TJ = 25oC
TA = TJ = 85oC
VIN = 5V, IOUT = 0.7A TA = TJ = 25oC
TA = TJ = 85oC
VIN = 5V, Switch Disabled, 50µA Load
RL = 10Ω, CL = 0.1µF, 10%-90%
RL = 10Ω, CL = 0.1µF, 90%-10%
RL = 1Ω, CL = 0.1µF, 90%-10%
Current Limit, VIN = 3.3V - 5V
Ilim VOUT = 0.8V
OC Regulation Settling Time
Severe OC Regulation Settling Time
Over Current Latch-off Time
I/O PARAMETERS
tsettIlim
tsettIlim_sev
tOC_loff
RL = 5Ω, CL = 0.1µF to Within 10% of CR
RL< 1Ω, CL = 0.1µF to Within 10% of CR
ISL6436X, TJ = 25oC
Fault Output Voltage
ENABLE High Threshold
Vfault_hi
Ven_vih
Fault IOUT = 10mA
VIN = 5.5V
ENABLE Low Threshold at 2.7V
Ven_vil VIN = 2.7V
ENABLE Low Threshold at 5.5V
ENABLE Input Current
BIAS PARAMETERS
Enabled VIN Current
Disabled VIN Current
Undervoltage Lockout Threshold
UV Hysteresis
Overtemperature Disable
Ven_vil
Ien_i
VIN = 5.5V
ENABLE = 0V to 5V, VIN = 5V, TJ >25oC
IVDD
IVDD
VUVLO
UVHYS
Temp_dis
Switches Closed, OUTPUT = OPEN, TJ >0oC
Switches Open, OUTPUT = OPEN
VIN Rising, Switch Enabled
MIN
-
-
-
-
-
-
-
-
-
-
0.75
-
-
-
-
2.0
-
-
-0.5
-
-
1.7
50
-
TYP
90
115
80
115
80
115
300
10
10
4
1
2
100
10
-
-
-
-
-
120
1
2.25
100
150
MAX UNITS
105 m
130 m
100 m
130 m
95 m
130 m
450 mV
- V/ms
- V/ms
- V/µs
1.25 A
- ms
- µs
- ms
0.4 V
-V
0.6 V
0.8 V
0.5 µA
200 µA
5 µA
2.5 V
- mV
- oC
Introduction
The ISL6436 is a fully independent dual channel overcurrent
(OC) fault protection IC for the +2.5V to +5.5V environment.
Each ISL6436 incorporates in a single 8 lead SOIC package
two 80mN-channel MOSFET power switches for power
control. Independent enabling inputs and fault reporting outputs
compatible with 3V and 5V logic allows for external control and
monitoring. This device features internal current monitoring,
accurate current limiting, integrated power switches and current
limited timed delay to latch-off for system protection. See Figure
1 for typical operational waveforms including both under and
over current situations.
Key Feature Description and Operation
4

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ISL6436
UV Lock Out
The ISL6436 undervoltage lockout feature prevents
functionality of the device unless the correct ENABLE state and
VIN > 2.5V are present.
Soft Start
A constant 500nA current source ramps up the switch’s gate
causing a voltage follower effect on the output voltage. This
provides a soft start turn-on eliminating bus voltage drooping
caused by in-rush current charging heavy load capacitances.
Rising and falling outputs are current limited voltage ramps so
that both the inrush current and voltage slew rate are limited,
independent of load. This reduces supply droop due to surge
and also eliminates the need for EMI filters necessary on other
IC products.
Fault Blanking On Start-Up
During initial turn-on the ISL6436 prevents nuisance faults
being reported to the system controller by blanking the fault
signal for 12ms. This blanking eliminates the need for external
RC filters necessary for other vendor products that assert a
fault signal upon initial turn-on into a temporary high current
condition. See Figures 10 through 12 for waveform examples.
Current Regulation
The ISL6436 has integrated current sensing on the power
MOSFET that allows for rapid control of OC events. Once an
OC is detected the ISL6436 goes into its current regulation
(CR) control mode. The ISL6436 CR level is set to a nominal
1A. This current regulation is ±25% over the full operating
temperature and voltage bias range. See Figures 4 and 5 for
illustrative curves. The speed of this control is inversely related
to the magnitude of the OC fault. Thus a hard over current is
more quickly controlled than a marginal OC condition. See
Figure 6 for waveforms illustrating this and Figure 7 for an
accompanying graph.
Over Temperature Shutdown
Although the ISL6436 has a thermal shutdown feature,
because of the 12ms timed shutdown this will only be invoked
in extremely high ambient temperatures.
Latch-Off Time Delay
The primary function of any OC protection device is to quickly
isolate the voltage bus from a faulty load. Unlike many other
IC products that sense the IC thermal condition (the monitored
IC junction temperature depends on a number of factors the
most important of which are power dissipation of the faulted
and adjacent switches and package temp) to isolate a faulty
load, the ISL6436 uses an internal 12ms timer that starts upon
OC detection. Once an OC condition is detected the
appropriate output is current limited for a maximum of 12ms to
allow transient conditions to pass before latch-off. This time to
latch-off is independent of device thermal or adjacent switch
condition. See Figure 18 for waveforms illustrating
independent latch-off.
If, after the ISL6436 has latched off, and the fault has asserted
and, the enable is not deasserted but the OC condition still
exists, the ISL6436 unlike other IC devices does not send to
the controller a continuous string of fault pulses. The
ISL6436’s single fault signal is sent at the time of latch-off
unlike other devices.
Slow And Fast Shutdown
The ISL6436 has two shutdown modes. When turned off
with a load current less than the current regulation (CR)
level the ISL6436 shuts down in a controlled manner using
a 500nA constant current source controlled ramp. When
latched off due to CR and the timer has expired, the
ISL6436 quickly pulls down the output thereby quickly
removing the faulted load from the voltage bus. See
Figures 8 and 9 for waveforms of each mode.
Active Output Pulldown
Another unique ISL6436 feature is the active pull down on
the outputs to 300mV above GND when the device is
disabled. Competitors’ parts’ switch leakage causes the
output voltage to drift up to VIN voltage even when the part
is supposed to be disabled.
ON OFF
ENABLE
FAULT
VOUT
LATCH-OFF SET
RESET BY
ENABLE
CURRENT
REGULATION
SETTLING TIME
(1.4ms)
OVER CURRENT
IOUT
1A CURRENT
LIMIT
12ms CURRENT REGULATION PERIOD
FIGURE 1. TYPICAL OPERATIONAL WAVEFORMS
5