ISL1801 Datasheet, PDF (16/30 Pages) Intersil Corporation – sPMIC for Micro Converter Bias and Drivers

ISL1801
Summary of Operation
The ISL1801 is a versatile Solar Power Management IC (sPMIC).
It has two switching regulators, two LDOs, two general purpose
comparators, two power MOSFET drivers, a current sense OPAMP
and other logic functions. Figure 17 shows the main blocks in the
ISL1801.
The high voltage LDO1 can be directly connected to a high
voltage input power source up to 90V. The output can be used to
start-up the high voltage switching regulator VR1. Once the VR1’s
output is greater than 6.7V, LDO1 is disabled to save power. The
second low voltage regulator, LDO2, can be connected to the
output of VR1 to generate the 5V supply required for the internal
control circuits including those that operate VR1 and VR2.
The first switching regulator, VR1, can be directly connected to an
input voltage up to 90V. The VR1 provides a regulated voltage for
the second switching regulator, VR2, and the two integrated
MOSFET drivers. The low voltage switching regulator, the VR2,
can be used to generate the regulated voltage for an MCU or
other external circuitry. The PGOOD2 signal is used to indicate
that VR2 output voltage is within the regulation window. The
output voltage of both VR1 and VR2 can be set through resistor
dividers at the FB1 and FB2 pins respectively. The switching
frequencies of VR1 and VR2 are determined by the resistors at
the TON1 and TON2 pins respectively.
There are two low-side drivers for the external power MOSFETs.
Both drivers are powered by the PVCC3 pin, which is normally
connected to the output of VR1.
The integrated amplifier has low offset and drift so, the MCU can
accurately sense the amplified module current.
Overcurrent and overvoltage conditions can be monitored by the
two general purpose high-speed comparators. Any detected fault
condition can be used to trigger an MCU interrupt.
The preload function is specially designed for solar applications.
It applies a resistive load to the input power source to verify that
it is sufficient for device operation. VR2, the MCU supply, will not
be enabled until the input power source has enough power. This
function can significantly reduce the power cycling of the MCU at
system start-up and shutdown.
The ISL1801 also includes a watchdog circuit to prevent the
software in the MCU from hanging in an unknown state. The MCU
can use the watchdog input (WDI) pin to periodically restart the
timer. The watchdog timeout is set by a resistor to VCC5V and a
capacitor to ground, both connected to the TIMER pin. If the RC
timer expires before an MCU reset on the WDI pin the PGOOD2
pin will be pulled low to reset the MCU.
MCU ^BCMD
MCU ^PWM3
MCU ^WDI
VCC5V
TIMER
VOUT1
ISL1801
HIGH
SPEED
DRIVER
PGOOD2
WATCHDOG
PRE-LOAD
CONTROL
+
- Vth2
- Vth3
+
ENABLE
VR2
VR1 ^VCC
1
PWM1
VCC
1
LDO1
PRELOAD
OPAMP AND
COMPARATORS
ENABLE
VR1
-
POR
PVCC3
VR2
VCC5
V
PWM2
LDO2
VCC5
V
PGOOD2
MCU
+ ^0.88*Vref2
-
PVCC3
BDRIVER _POWER
MOSFET
DRIVER3 _POWER
MOSFET
VIN1
PV
PANEL
VOUT1
L1 (10V)
VCC1
FB1
VIN2
VOUT2
L2 (3.3V)
VCC5V
FB2
FIGURE 17. ISL1801 SIMPLIFIED BLOCK DIAGRAM
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FN8259.1
July 24, 2014