ISL6436 Datasheet, PDF (9/12 Pages) Intersil Corporation – USB Dual Port Power Supply Controller

ISL6436
Using the ISL6436EVAL1 Platform
General and Biasing Information
The ISL6436EVAL1 platform, Figure 19, allows evaluation of
the ISL6436 dual power supply control IC and comparison
against a suitably sized PPTC component.
The evaluation platform is biased and monitored through
numerous test points (TP#). See Table 1 for test point
assignments and descriptions.
TABLE 1. ISL6436EVAL1 TEST POINT ASSIGNMENTS
TP #
DESCRIPTION
TP1
Eval Board and IC GND
TP2
Eval Bd +5V Bias
TP3
Enable Switch 1
TP4
Enable Switch 2
TP5
Switch 2 Fault
TP6
Switch Out 2
TP7
Switch Out 1
TP8
Switch 1 Fault
TP9
IC VIN Pin
TP10
PPTC Load Side
TP11
Invoke Overcurrent
Upon proper bias the PPTC, F1 has a nominal 500mA load
current passing through it which is the hold current rating for
that particular device. Removal of the PPTC is necessary to
isolate the ISL6436 as the PPTC load current is common to
the ISL6436EVAL1 bias connections.
By enabling either or both of the ISL6436L switches by
signaling TP3 and / or TP4 low (<0.6V) these switches are
also loaded with a nominal 500mA current. See Figures 3
and 8 for typical ISL6436 turn-on and off waveforms.
Provided test points enable the evaluation of voltage loss
across the PPTC (TP9 - TP10) and the ISL6436 enabled
switches (TP9 - TP6 and TP7). Expect to see 50% - 300%
greater voltage loss across typical PPTCs devices than the
ISL6436. See Figure 13 for a voltage loss comparison
across ISL6436 and PPTC device.
An overcurrent (OC) condition can be invoked on both the
ISL6436 and the PPTC by driving TP11 to +6V, causing SW1
to close and a nominal 1.5A load is imposed. This represents
a current over load to the ISL6436 and is thus quickly current
regulated to the 1A limit. If the OC duration extends beyond
the nominal 12ms of the internal ISL6436L timer then the
output is latched off and the fault output is asserted by being
pulled low turning on the appropriate FAULT LED, see Figure
10. (Please note: the labeling for FAULT-1 and FAULT-2 is
reversed). The eval board is designed to only invoke an OC
condition on channel 2 (TP4) so that a channel to channel
isolation evaluation in the presence of an OC condition can be
evaluated. See Figure 18.
The primary function of any OC protection device is to
quickly isolate the voltage bus from a faulty load. Unlike the
PPTC and other vendor available IC products, the ISL6436
internal timer that starts upon OC detection provides
consistent protection that is not temperature dependent. See
Figures 14 and 15 for a comparison of the time to protection
offered by the ISL6436 vs the PPTC. Figure 14 illustrates the
ISL6436 timed latch-off of 12mS with a 1.5A load and Figure
15 shows the 8s latch-off of the PPTC at approximately its
trip current rating of 1.5A.
Using the ISL6436USBEVAL1 Platform
General and Biasing Information
The ISL6436USBEVAL1 platform, Figure 20 allows
evaluation of the ISL6436 dual power supply control IC in an
USB environment.
The evaluation platform is biased and monitored through
numerous test points (TP#), see Table 2 for test point
assignments and descriptions.
TABLE 2. ISL6436USBEVAL1 TEST POINT ASSIGNMENTS
TP #
DESCRIPTION
TP1
Eval Board and IC GND
TP2
Eval Bd +5V Bias
TP3
Enable Switch 1
TP4
Enable Switch 2
TP5
Switch 1 Fault
TP8
Switch 2 Fault
Upon proper bias the ISL6436L is held off through pull up
resistors on the enable pins and is enabled by signaling
either or both of the ISL6436L switches TP3, and / or TP4
low (<0.6V).
The USB connector is provided so that either test loads or
USB peripherals can be powered. In addition, differential
signalling (D+ and D-) access points are provided for each
output port so that I/O activity can also be conducted in a
prototype environment.
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