ISL6236A Datasheet, PDF (31/37 Pages) Intersil Corporation – High-Efficiency, Quad-Output, Main Power Supply Controllers for Notebook Computers

ISL6236A
Power-Up Sequencing and On/Off Controls (EN )
EN1 and EN2 control SMPS power-up sequencing. EN1 or
EN2 rising above 2.4V enables the respective outputs. EN1
or EN2 falling below 1.6V disables the respective outputs.
Connecting EN1 or EN2 to REF will force its outputs off while
the other output is below regulation. The sequenced SMPS
will start once the other SMPS reaches regulation. The
second SMPS remains on until the first SMPS turns off, the
device shuts down, a fault occurs or PVCC goes into
undervoltage lockout. Both supplies begin their power-down
sequence immediately when the first supply turns off. Driving
EN below 0.8V clears the overvoltage, undervoltage and
thermal fault latches.
MODE
Power-Up
Run
Overvoltage
Protection
Undervoltage
Protection
Discharge
Standby
Shutdown
Thermal Shutdown
TABLE 3. OPERATING-MODE TRUTH TABLE
CONDITION
COMMENT
PVCC < UVLO threshold.
Transitions to discharge mode after a VIN POR and after REF becomes valid. LDO,
VREF3 and REF remain active.
EN LDO = high, EN1 or EN2
enabled.
Normal operation
Either output > 111% (VOUT1) or
116% (VOUT2) of nominal level.
LGATE is forced high. LDO, VREF3 and REF active. Exited by a VIN POR, or by
toggling EN1 or EN2.
Either output < 70% of nominal after The internal 25Ω switch turns on. LDO, VREF3 and REF are active. Exited by a VIN
20ms time-out expires and output is POR or by toggling EN1 or EN2.
enabled.
Either SMPS output is still high in
either standby mode or shutdown
mode
Discharge switch (25Ω) connects OUT to GND. One output may still run while the
other is in discharge mode. Activates when PVCC is in UVLO, or transition to UVLO,
standby, or shutdown has begun. LDO, VREF3 and REF active.
EN1, EN2 < start-up threshold, EN LDO, VREF3 and REF active.
LDO = High
EN1, EN2, EN LDO = low
Discharge switch (25Ω) connects OUT to PGND. All circuitry off except VREF3.
TJ > +150°C
All circuitry off. Exited by VIN POR or cycling EN. VREF3 remain active.
VEN LDO
Low
“>2.5” → High
“>2.5” → High
“>2.5” → High
“>2.5” → High
“>2.5” → High
“>2.5” → High
VEN1 (V)
Low
Low
High
High
Low
High
REF
TABLE 4. SHUTDOWN AND STANDBY CONTROL LOGIS
VEN2 (V)
LDO
SMPS1
Low
Off
Off
Low
On
Off
High
On
On
Low
On
On
High
On
Off
REF
On
On
High
On
On (after SMPS2 is up)
SMPS2
Off
Off
On
Off
On
On (after SMPS1 is up)
On
31
FN6453.3
March 18, 2008