an1218

ISL9200EVAL1 Application Note
®
Application Note
November 17, 2005
AN1218.0
Author: Chuck Wong
Introduction
Design Specification
The ISL9200EVAL1 is the evaluation board for the ISL9200
double-fault tolerant charging system solution. The
components for the entire solution are placed inside the
white rectangular box (see Figure 1). The system mainly
consists of the ISL6292C charging IC and the ISL9200
protection IC. The ISL6292C is an integrated Li-ion battery
charger with the charge current set at 0.5A (refer to the
ISL6292C datasheet for more information). The ISL9200
protects the charging system against three types of failures:
The design specifications are given in Table 1.
• Input overvoltage when the AC adapter fails to regulate its
voltage under 6.5V;
• Load overcurrent when failures such as a short circuit
occurs in the charging system;
• Battery over charge.
When any single failure occurs in the charging system, the
ISL6292C Output node will not output a voltage higher than
4.5V nor a current higher than the set current limit (1A for
this board).
As shown in Figure 1, the evaluation board has multiple test
points for the convenience of evaluation. The upper half of
the board contains connectors for the power connection. The
lower half contains test points for easy access to various
pins of the two ICs.
This application note introduces the ISL9200EVAL1
evaluation board and the ISL9200 behavior based on the
board.
ISL9200EVAL1 Photo
TABLE 1. DESIGN SPECIFICATIONS
SPECIFICATION
MIN
TYP
6.5
6.8
7.0
V
Overcurrent Protection Threshold
-
1.0
-
A
Battery OVP Threshold
-
4.4
4.5
V
Input Voltage
-
-
30
V
Charge Current
-
0.5
-
A
4.20
4.25
4.30
V
Input OVP Threshold
Charger Output Voltage
MAX UNIT
Schematic, Layout, and BOM
The schematic, layout and the BOM for the evaluation board
are shown in Figures 21, 22, and Table 2 respectively.
Evaluation Waveforms
This section introduce the waveforms captured using the
ISL9200EVAL1 to verify the functionality of the ISL9200.
Power-up
There are two ways to power-up the evaluation board. One
way is to connect an ac adapter or the power supply to the
evaluation board and then turn on the power. The second
way is to connect the supply to the evaluation board after the
supply is powered up (hot insertion).
Figure 2 shows the first way. Approximately 10ms after the
input voltage rises to 5V, the ISL9200 begins the soft-start
process. The 10ms delay allows any transient to settle down
before the start-up, which is demonstrated during the hot
insertion. The blue waveform is the load current into a 10Ω
resistive load.
Figure 3 shows the captured waveforms during the hot
insertion of the power supply. The input overshoot caused by
the resonance of the parasitic inductance of the supply cable
and the ceramic input decoupling capacitor is clearly shown.
Figure 4 shows the zoomed-in view of Figure 3 at the powerup moment. The transient is completed before the ISL9200
starts to turn on.
FIGURE 1. PHOTO OF THE ISL9200EVAL1
1
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Application Note 1218
Evaluation Waveforms
Input Overshoot
VIN (1V/div)
OUT (1V/div)
VIN (2V/div)
OUT (2V/div)
Load Current
(200mA/div)
Time: 5ms/div
FIGURE 2. CAPTURED WAVEFORMS FOR POWER-UP. THE
OUTPUT IS LOADED WITH A 10Ω RESISTOR
Load Current
(500mA/div)
Time: 10ms/div
FIGURE 3. CAPTURED WAVEFORMS FOR HOT INSERTION
OF THE POWER SUPPLY
Time: 200ms/div
Input Overshoot
VIN (2V/div)
VIN (2V/div)
OUT (2V/div)
Time: 20μs/div
FIGURE 4. ZOOMED-IN VIEW OF FIGURE 3
WRN (5V/div)
FIGURE 5. THE INPUT RISES GRADUALLY AND EXCEEDS
THE INPUT OVP THRESHOLD
VIN (2V/div)
VIN (2V/div)
OUT (2V/div)
OUT (2V/div)
WRN (5V/div)
WRN (5V/div)
Time: 5μs/div
FIGURE 6. THE ZOOMED-IN VIEW OF FIGURE 5
2
Time: 5ms/div
FIGURE 7. THE INPUT RISES GRADUALLY AND EXCEEDS
THE INPUT OVP THRESHOLD
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Evaluation Waveforms
(Continued)
VIN (2V/div)
VIN (2V/div)
OUT (2V/div)
OUT (2V/div)
ILIM (1V/div)
WRN (5V/div)
WRN (5V/div) Time: 500μs/div
Time: 2μs/div
FIGURE 8. THE INPUT RISES QUICKLY FROM 6.5V TO 10.5V
FIGURE 9. TRANSIENT WAVEFORMS WHEN INPUT STEPS
FROM 0V TO 9V
Time: 100μs/div
VIN (2V/div)
VIN (2V/div)
OUT (2V/div)
OUT (2V/div)
Time: 500μs/div
VB (5V/div)
VB (5V/div)
WRN (5V/div)
WRN (5V/div)
FIGURE 10. NO REACTION TO THE 0V TO 5V VB-PIN
VOLTAGE WHEN THE PULSE WIDTH IS LESS
THAN THE BLANKING TIME
Time: 20s/div
VIN (1V/div)
FIGURE 11. THE ISL9200 TURNS OFF THE OUTPUT WHEN VB
VOLTAGE EXCEEDS 160μs
Time: 200ms/div
VIN (1V/div)
VB (1V/div)
OUT (1V/div)
OUT (1V/div)
Load Current
(500mA/div)
WRN (5V/div)
WRN (5V/div)
FIGURE 12. THE ISL9200 LATCHES OFF AFTER 16-COUNT
OF BATTERY OVP
3
FIGURE 13. THE POWER-UP WAVEFORMS WHEN THE
OUTPUT IS OVER-LOADED WITH A 3Ω
RESISTOR
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Application Note 1218
Evaluation Waveforms
(Continued)
Time: 10ms/div
VIN (1V/div)
Time: 200ms/div
VIN (1V/div)
OUT (1V/div)
OUT (1V/div)
Load Current
(500mA/div)
Load Current
(500mA/div)
WRN (5V/div)
WRN (5V/div)
FIGURE 14. THE ZOOMED-IN VIEW OF FIGURE 13
Time: 10ms/div
VIN (1V/div)
FIGURE 15. THE POWER-UP WAVEFORMS WHEN THE
OUTPUT IS SHORT-CIRCUITED
Time: 200μs/div
VIN (1V/div)
OUT (1V/div)
Load Current
(500mA/div)
Load Current
(500mA/div)
OUT (1V/div)
WRN (5V/div)
WRN (5V/div)
FIGURE 16. THE ZOOMED-IN VIEW OF FIGURE 15
FIGURE 17. THE ZOOMED-IN VIEW OF FIGURE 18
Time: 200ms/div
Time: 200ms/div
VIN (1V/div)
VIN (1V/div)
OUT (1V/div)
Load Current
(500mA/div)
WRN (5V/div)
FIGURE 18. THE 3Ω RESISTOR OVER LOAD OCCURS AFTER
THE POWER IS ON
4
Load Current
(2A/div)
OUT (1V/div)
WRN (5V/div)
FIGURE 19. SHORT-CIRCUIT HAPPENS AFTER THE INPUT
POWER IS UP
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Application Note 1218
Evaluation Waveforms
(Continued)
VIN (1V/div)
Load Current
(2A/div)
OUT (1V/div)
Time: 10μs/div
WRN (5V/div)
FIGURE 20. THE ZOOMED-IN VIEW OF FIGURE 19
Input Over-Voltage Protection (OVP)
The ISL9200 turns off the internal power FET when the input
voltage exceeds the input OVP threshold to protect other
electronics in the system. Figure 5 shows the action when
the input is exceeding the OVP threshold gradually. The
output voltage falls to ground after and the WRN logic signal
turns to low. Figure 6 is a zoomed-in view to show more
details during the transition. The ISL9200 was conducting
0.5A before the protection is triggered. When the OVP is
triggered, the input voltage signal has a ringing due the
parasitic cable inductance. The OVP threshold typically has
a 100mV hysteresis. The WRN signal has a narrow pulse
after the OVP because the ringing of the input voltage signal
exceeds the hysteresis during the first cycle.
Figure 7 shows the waveforms when the input voltage drops
below the falling threshold for the input OVP. The WRN
signal rises immediately to show the removal of the input
overvoltage situation but the output rises after the 10ms
delay.
When the input voltage exceeds the OVP threshold, the
internal power FET is turned off within 1μs. Figure 8 shows
the behavior when the input voltage rises quickly from 6.5V
to 10.5V. The time scale is 2μs/div and the reaction time is
well within 1μs.
When a power supply that is already failed (unable to
regulate the output below 6.5V) is used to power-up the
ISL9200, the high input voltage will not show up at the
ISL9200 output at all. Figure 9 illustrates such case. A 9V
supply is used to power-up. The ISL9200 starts to operate
once the input voltage exceeds the POR threshold, as
indicated by the ILIM and the WRN pin voltages, but the
internal power FET does not start to turn on before the end
of the 10ms delay. Since the input voltage rises above the
OVP threshold within 10ms, the OVP is issued before the
soft-start process. The failed supply voltage will never show
up at the OUT pin in this case.
5
Battery Overvoltage Protection
The battery OVP function is to prevent over-charge of the Liion battery. The typical protection threshold is 4.4V. There is
a blanking time of approximately 160μs to prevent triggering
of the battery OVP by a transient voltage. Only when the
battery voltage exceeds the threshold for longer than the
blanking time, will the OVP be triggered. The ISL9200 also
has a 4-bit binary counter to count the battery OVP event.
The internal power FET will be permanently latched off if the
battery OVP event exceeds 16 counts. Then IC can then be
reset only by cycling the input power or the enable input pin.
Figure 10 to Figure 12 illustrate the battery OVP behavior.
Figure 10 shows the captured waveforms when the VB-pin
voltage pulses between 0V and 5V but the pulse width is
less than the blanking time. The ISL9200 does not react to
the VB-pin overvoltage in this case. Figure 11 shows the
case that the pulse width barely exceeds the blanking time.
The battery OVP is triggered, as indicated by the falling
voltage on the OUT pin. A very narrow pulse can be found at
the falling edge of the VB pulse. Figure 12 illustrates the
latch off of the ISL9200 after 16-count of the battery OVP
events. The VB pin voltage changes between 4.3V to 4.5V
for 20 times but the IC does not react to the VB voltage after
16 counts.
Overcurrent Protection (OCP)
The ISL9200EVAL1 sets the overcurrent protection
threshold at 1A. When the current in the internal power FET
exceeds 1A, the power FET is turned off. The ISL9200 tries
to soft-start again after approximately 60ms. Same as the
battery OVP event, an internal 4-bit binary counter sets the
limit of 16 counts for the OCP event before latching off. The
OCP also has a blanking time to prevent any transient
current from triggering the protection.
The behavior of the ISL9200 is slightly different between the
cases that the output is over-loaded before and after the
input power is up. When the over-load exists before the input
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Application Note 1218
power is up, the over load will be detected during the softstart. The gate voltage of the internal power FET is
controlled near the gate threshold voltage during the soft
start; hence the FET current is controlled and is not capable
to rise very fast. If the load current stays above the OCP
threshold for longer than the blanking time, the power FET is
turned off. Figure 13 to Figure 16 show the captured
waveforms during the power-up. The output is over loaded
with a 3Ω resistor and a hard short-circuit respectively. Both
cases the ISL9200 is latched off after 16 attempts of soft
start. The zoomed-in views show the difference in the output
voltage, one rises proportionally to the current and the other
one shorted to ground all the time. For both cases, the peak
load current is only slightly higher than the 1A limit.
and Figure 16. The high current when a hard short-circuit is
happening after the power is up does not flow through the
battery so is not a hazardous condition to the Li-ion battery.
Summary
This application note introduced the schematics, layout, and
BOM of the ISL9200EVAL1 evaluation board for the
ISL9200. Captured scope waveforms during power-up, input
OVP, battery OVP and output OCP cases are shown to
demonstrate the robustness of the ISL9200. The FMEA
document for the charging system using the two chips of this
evaluation board will be available upon request to further
prove the safety of the ISL9200 solution.
If the input power is already on, the internal power FET is
fully turned on and the gate voltage has passed the gate
threshold voltage. When an over load case occurs, there is a
delay for the gate voltage to move to the gate threshold
voltage. Before reaching the gate threshold voltage, the
power FET remains fully on, hence the current in the FET is
totally dependent on the conditions outside the ISL9200.
Figure 18 illustrates the behavior that the output is loaded
with a 3Ω resistor after the power is on. The ISL9200 still
latches off after 16 count of OCP. After every OCP, the IC
starts softly, hence the waveforms are same as those in
Figure 14. The only difference happens during the first OCP
event.
Figure 17 shows the zoomed-in view of the first OCP event.
The current rises to the level limited by the 3Ω resistor and
other parasitics. Note that the input voltage stays above the
POR threshold since this case represents a minor
overcurrent situation.
When a hard short-circuit event happens after the power is
up, the overcurrent during the initial pulse is more severe.
Figure 19 illustrate the case that the output is short-circuited
after the IC is powered up. Note that the current waveform
has 17 pulses with the first pulse very close to the second
one on the time scale but the magnitude is significantly
higher than the second and the rest. The current scale is
changed to 2A/div in order to see the magnitude of the first
pulse.
Figure 20 shows the zoomed-in view of the first pulse. For
the same reason, the power FET is fully turned on when the
short-circuit occurs and the current is totally depended on
the conditions outside the ISL9200. Since the output is a
short circuit, the current is totally dependent on the
parasitics. The current is Figure 20 shoots up more than 4A.
Note that the input voltage is pulled under the POR threshold
due to the high current; hence the IC is actually reset during
the first pulse. That is the explanation why there are 17
current pulses in this case. Once the initial overcurrent event
is finished, the ISL9200 begins the soft-start process. The
rest of the waveforms are the same as the ones in Figure 15
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Application Note 1218
FIGURE 21. SCHEMATICS FOR THE EVALUATION BOARD
(B) TOP LAYER
(A) SILK SCREEN LAYER
(C) BOTTOM LAYER
FIGURE 22. LAYOUT FOR THE EVALUATION BOARD
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Application Note 1218
TABLE 2. BILL-OF-MATERIAL FOR THE ISL9200 EVALUATION BOARD
ITEM #
QTY
REFERENCE
1
1
C1
2
5
3
PART #
PACKAGE
VENDOR
1µF, 16V, X5R
PCC2224CT-ND
0603
Digikey
C2, C4, C5, C7, C8
1µF, 6.3V, X5R
PCC1915CT-ND
0603
Digikey
1
C3
22nF, 16V, X7R
PCC1754CT-ND
0603
Digikey
4
1
C6
4.7µF, 16V, X5R
PCC2323CT-ND
0805
Digikey
5
3
R1, R5, R7
10k, 1%
P10.0KHCT-ND
0603
Digikey
6
1
R2
25.5k, 1%
311-25.5KHCT-ND
0603
Digikey
7
1
R3
470Ω, 5%
311-470HCT-ND
0603
Digikey
8
1
R4
200k, 1%
311-200KHCT-ND
0603
Digikey
9
1
R6
160k, 1%
311-160KHCT-ND
0603
Digikey
10
1
D1
Red LED
67-1552-1-ND
0805
Digikey
11
1
J1
Jumper
A19423-ND
Digikey
12
1
Shunt
S9001-ND
Digikey
13
4
Test Points - Black
5011K-ND
Digikey
14
6
ISL6292C OUTPUT(2),
Test Points - Red
VIN(2), VCC, ISL9200 OUT
5010K-ND
Digikey
15
7
WRN, ILIM, EN, VB, FAULT, Test Points - Yellow
EN, STATUS
5014K-ND
Digikey
16
1
U1
Charging System Protection IC
17
1
U2
Li-ion Battery Charger
GND(4)
DESCRIPTION
ISL9200
4X3 DFN
Intersil
ISL6292C
3X3 DFN
Intersil
NOTE: Do not populate C6, C7, and C8.
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Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
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