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Renesas Electronics Components Datasheet

ISL6446 Datasheet

Dual PWM and Linear Controller

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DATASHEET
ISL6446
Dual (180°Out-of-Phase) PWM and Linear Controller
The ISL6446 is a high-performance, triple output controller
that provides a single high-frequency power solution primarily
for broadband, DSL and networking applications. This device
integrates complete control, monitoring and protection
functions for two synchronous buck PWM controllers and one
linear controller. Input voltage ripple and total RMS input
current is substantially reduced by synchronized 180°
out-of-phase operation of the two PWMs.
The two PWM buck converters provide simple voltage mode
control. The output voltage of the converters can be precisely
regulated to as low as 0.6V, with a maximum tolerance of
±1.5% over-temperature and line variations. Programmable
switching frequency down to 100kHz provides optimized low
cost solution for ATX power supplies. It’s also able to operate
up to 2.5MHz to deliver compact solutions. The linear
controller provides a low-current output.
Each PWM controller has soft-start and independent enable
functions combined on a single pin. A capacitor from SS/EN to
ground sets the soft-start time; pulling SS/EN pin below 1V
disables the controller. Both outputs can soft-start into a
prebiased load.
The ISL6446 incorporates robust protection features. An
adjustable overcurrent protection circuit monitors the output
current by sensing the voltage drop across the upper MOSFET
rDS(ON). Latch-off mode overcurrent operation protects the
DC/DC converters from damage under overload and
short-circuit conditions. A PGOOD signal is issued when
soft-start is complete and PWM outputs are within 10% of
their regulated values and the linear regulator output is higher
than 75% of its nominal value. Thermal shutdown circuitry
turns the device off if the IC temperature exceeds +150°C.
FN7944
Rev 2.00
October 12, 2015
Features
• 4.5V to 5.5V or 5.5V to 24V input voltage range
• Three programmable power output voltages
- Two PWM controllers with out-of-phase operation
- Voltage-mode PWM control
- One linear controller
• Programmable switching frequency from 100kHz to 2.5MHz
• Fast transient response
- High-bandwidth error amplifier
• Extensive circuit protection functions
- Undervoltage and over-temperature
- Overvoltage with latch-off mode
- Programmable overcurrent limit with latch-off mode
- Lossless current sensing (no sense resistor needed)
• Externally adjustable soft-start time
- Independent enable control
- Voltage tracking capability
- Able to soft-start into a prebiased load
• PGOOD output with delay
Applications
• ATX power supplies
• DSP, ASIC and FPGA point of load regulation
• Industrial and security networking applications
VOUT1
VOUT2
Feedback
and
Compensation
Network
R1
Feedback
and
Compensation
Network
R2
VCC VIN
CVCC
ROCSET1
VCC
COMP1
FB1
VIN
OCSET1
BOOT1
UGATE1
CBOOT1
Q1
VIN1 = VIN
COCSET1
CIN1
COMP2
PHASE1
LGATE1
Q2
L1
VOUT1
COUT1
FB2
ISL6446
ROCSET2
VIN2 = VIN
OCSET2
BOOT2
UGATE2
CBOOT2
Q3
COCSET2
CIN2
PGOOD
RT
PHASE2
LGATE2
Q4
L2
VOUT2
COUT2
SS1/EN1
SS2/EN2
LCDR
LCFB
SGND PGND
FIGURE 1. TYPICAL APPLICATION
FN7944 Rev 2.00
October 12, 2015
100
98
96
94
92
90 VOUT = 3.3V
VOUT = 5V
88
86
84
82
80 0 5 10 15 20 25
LOAD CURRENT (A)
FIGURE 2. EFFICIENCY vs LOAD CURRENT (OBTAINED FROM
ISL6446EVAL1Z)
Page 1 of 19


Renesas Electronics Components Datasheet

ISL6446 Datasheet

Dual PWM and Linear Controller

No Preview Available !

ISL6446
Pin Configuration
ISL6446
(24 LD QSOP)
TOP VIEW
OCSET1 1
SS1/EN1 2
COMP1 3
FB1 4
RT 5
SGND 6
LCDR 7
LCFB 8
FB2 9
COMP2 10
SS2/EN2 11
OCSET2 12
24 VIN
23 BOOT1
22 UGATE1
21 PHASE1
20 LGATE1
19 VCC
18 PGND
17 LGATE2
16 PHASE2
15 UGATE2
14 BOOT2
13 PGOOD
Pin Descriptions
SYMBOL PIN #
DESCRIPTION
BOOT2, 1 14, 23 These pins power are the upper MOSFET drivers of each PWM converter. The anode of each internal bootstrap diode is connected
to the VCC pin. The cathode of the bootstrap diode is connected to this pin, which should also connect to the bootstrap capacitor.
UGATE2, 1 15, 22 These pins provide the gate drive for upper MOSFETs, bootstrapped from the VCC pin.
PHASE2, 1 16, 21 These are the junction points of the upper MOSFET sources, the output filter inductor and lower MOSFET drains. Connect these
pins accordingly to the respective converter.
LGATE2, 1 17, 20 These are the outputs of the lower N-Channel MOSFET drivers, sourced from the VCC pin.
PGND
18 This pin provides the power ground connection for the lower gate drivers. This pin should be connected to the source of the lower
MOSFET for PWM1 and PWM2 and the negative terminals of the external input capacitors.
FB1, 2
4, 9 These pins are connected to the feedback resistor divider and provide the voltage feedback signals for the respective controller. They
set the output voltage of the converter. In addition, the PGOOD circuit and OVP circuit use these inputs to monitor the output voltage
status.
COMP1, 2 3, 10 These pins are the error amplifier outputs for the respective PWM. They are used, along with the FB pins, as the compensation point
for the PWM error amplifier.
PGOOD
13 This is an open drain logic output used to indicate the status of the output voltages. This pin is pulled low when either of the two
PWM outputs is not within 10% of the respective nominal voltage or when the linear output drops below 75% of its nominal voltage.
To maintain the PGOOD function if the linear output is not used, connect LCFB to VCC.
SGND
6 This is the signal ground, common to both controllers, and must be routed separately from the high current grounds (PGND). All
voltage levels are measured with respect to this pin.
VIN 24 This pin powers the controllers with an internal linear regulator (if VIN > 5.5V) and must be closely decoupled to ground using a
ceramic capacitor as close to the VIN pin as possible. The VIN is the input voltage applied to the upper FET of both converters.
TABLE 1. INPUT SUPPLY CONFIGURATION
INPUT
PIN CONFIGURATION
5.5V to 24V
Connect the input supply to the VIN pin. The VCC
pin will provide a 5V output from the internal
voltage regulator.
5V ±10%
Connect the input supply to the VCC pin.
VCC 19 This pin supplies the bias for the regulators, powers the low-side gate drivers and external boot circuitry for high-side gate drivers.
The IC may be powered directly from a single 5V (±10%) supply at this pin; when used as a 5V supply input, this pin must be
externally connected to VIN. When VIN > 5.5, VCC is the output of the internal 5V linear regulator output. The VCC pin must always
be decoupled to power ground with a minimum of 1µF ceramic capacitor, placed very close to the pin.
FN7944 Rev 2.00
October 12, 2015
Page 2 of 19


Part Number ISL6446
Description Dual PWM and Linear Controller
Maker Renesas
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ISL6446 Datasheet PDF






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