ISL97684IRTZ 查看數據表（PDF） - Intersil
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ISL97684IRTZ Datasheet PDF : 17 Pages
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ISL97682, ISL97683, ISL97684
VIN
LX
VOUT
IMAX ILIMIT
LOGIC
O/P
SHORT
FET
DRIVER
OVP
VIN
VSET/2
VSC
CH4
REG
THRM
SHDN
REF
OTP
T2
TEMP
SENSOR
T1
VSET +
Q1 VSET +
Q4
-
-
PHASE SHIFT
AND LOGIC
CONTROL
PWM1/OC1/SC1
PWM4/OC4/SC4
FIGURE 25. SIMPLIFIED FAULT PROTECTIONS
CASE
1
2
3
4
5
6
7
8
9
FAILURE MODE
CH1 Short Circuit
CH1 Short Circuit
CH1 Short Circuit
CH1 Open Circuit
with infinite
resistance
CH1 LED Open
Circuit but has
paralleled Zener
CH1 LED Open
Circuit but has
paralleled Zener
CH1 LED Open
Circuit but has
paralleled Zener
Channel-to-Channel
ΔVF too high
Output LED stack
voltage too high
TABLE 3. PROTECTIONS TABLE
DETECTION MODE
FAILED CHANNEL ACTION
GOOD CHANNELS ACTION
VOUT REGULATED
BY
Over-Temperature
CH1 ON and burns power
Protection limit (OTP) not
triggered and CH1 < 4.4V
CH2 through CH4 Normal
Highest VF of CH2
through CH4
OTP triggered but VCH1 < All channels switched off until power-cycled.
4.4V
Highest VF of CH2
through CH4
OTP not triggered but
CH1 > 4.4V
CH1 faults out after 6 PWM cycle CH2 through CH4 Normal
(7-18 in direct PWM) time-out
Highest VF of CH2
through CH4
OTP not triggered and
CH1 < 4.4V
VOUT will ramp to OVP. CH1 will
time-out after 6 PWM cycles (7-18
in direct PWM) and switch off. VOUT
will drop to normal level.
CH2 through CH4 Normal
Highest VF of CH2
through CH4
OTP not triggered and
CH1 < 4.4V
CH1 remains ON and has highest CH2 through CH4 ON, Q2 through VF of CH1
VF, thus VOUT increases
Q4 burn power
OTP triggered but CH1 < CH1 goes off
4.4V
Same as CH1
VF of CH1
OTP not triggered but
CHx > 4.4V
CH1 remains ON and has highest
VF, thus VOUT increases.
VOUT increases then CH-X
switches OFF after 6 PWM cycles.
This is an unwanted shut off and
can be prevented by setting OVP
at an appropriate level.
VF of CH1
OTP triggered but CHx < All channels switched off until chip cooled
4.4V
Highest VF of CH1
through CH4
VOUT > VOVP
Driven with normal current. Any channel that has insufficient headroom Highest VF of CH1
will fault out after 6 PWM cycle (7-18 in direct PWM) time-out.
through CH4
14
FN7689.0
March 11, 2011
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