InnoSwitch3-MX
Family
Off-Line Multiple Output QR Flyback Switcher IC with
Integrated 650 V, 725 V or 750 V Switch, Synchronous
Rectification and FluxLink Feedback
Product Highlights
•
High efficiency across full load range
•
Incorporates a multi-mode Quasi-Resonant (QR) / CCM flyback
controller, 650 V, 725 V or 750 V switch, secondary-side sensing and
synchronous rectification driver
• PowiGaN™ technology – up to 85 W without heat sink
(INN3478C, INN3479C and INN3470C)
• Integrated FluxLink™, HIPOT-isolated, feedback link
• Instantaneous transient response ±5% CV with 0%-100%-0%
load step
• Partner IC to InnoMux
VLED
Based on InnoSwitch3
VOUT2
VOUT1
RTN
VCV1
EcoSmart™ – Energy Efficient
•
Easily meets all global energy efficiency regulations
• Low heat dissipation
VOUT
BPS
BPS
FW
Advanced Protection / Safety Features
•
•
•
•
InnoSwitch3-MX
Primary FET
and Controller
D
V
SR
GND
Primary sensed output OVP
Open SR FET gate detection
Hysteretic thermal shutdown
Input voltage monitor with accurate brown-in/brown-out and
overvoltage protection
Reinforced insulation
Isolation voltage >4000 VAC
100% production HIPOT compliance testing
UL1577 and TUV (EN60950) safety approved
Enables designs that have “A” performance criteria for EN61000-4
suite of test standards, including EN61000-4-2, 4-3 (30 V/m), 4-4,
4-5, 4-6, 4-8 (100 A/m) and 4-9 (1000 A/m)
SR
FWC
REQ
ACK
Interface
with
InnoMux
S
BPP
Secondary
Control IC
PI-8368c-030920
Full Safety and Regulatory Compliance
•
•
•
•
•
Figure 1.
Typical Application/Performance.
Figure 2.
High Creepage, Safety-Compliant InSOP-24D Package.
Wave Solder or Reflow Process.
Green Package
Applications
• Halogen free and RoHS compliant
• Use with InnoMux for Energy Star 8, CEC, and 2021/2023 EU
labeling for monitors and TVs
Output Power Table
Product
3
BV
Rating
650 V
650 / 725 V
650 / 725 V
650 / 725 V
650 V
750 V
750 V
750 V
85-265 VAC
Nominal
Continuous
1
18 W
22 W
28 W
35 W
40 W
55 W
65 W
75 W
Max
Continuous
2
23 W
28 W
35 W
44 W
50 W
65 W
75 W
85 W
Description
The InnoSwitch3-MX
together with InnoMux dramatically improves
system efficiency by eliminating the boost and buck converter stages.
It also simplifies the development and manufacturing of multiple output
power supplies, particularly those in compact enclosures or with high
efficiency requirements. The InnoSwitch3-MX architecture is revolu-
tionary in that the devices incorporate both primary and secondary
controllers, with sense elements and a safety-rated feedback mecha-
nism into a single IC.
Close component proximity and innovative use of the integrated
communication link, FluxLink, permit accurate control of a secondary-
side synchronous rectification MOSFET with Quasi-Resonant switching
of primary integrated high-voltage switch to maintain high efficiency
across the entire load range.
This version of InnoSwitch3 is intended to be used with InnoMux for
multiple output, single-stage power supplies for monitors and TVs.
This enables very high system efficiency on a small PCB foot print.
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INN3464C
INN34x5C
INN34x6C
INN34x7C
INN3468C
INN3478C
INN3479C
INN3470C
Table 1.
Output Power Table.
Notes:
1. Continuous power using nominal primary current limit in a typical open frame
application at +50 °C ambient with adequate PCB thermal design to ensure
package temperature <125 °C.
2. Continuous power using maximum primary current limit in a typical open
frame application at +50 °C ambient with adequate heat sinking to ensure
package temperature <125 °C.
3. Package: InSOP-24D.
March 2020
This Product is Covered by Patents and/or Pending Patent Applications.
InnoSwitch3-MX
Pin Functional Description
InnoSwitch3-MX
REQUEST (REQ) Pin (Pin 1)
Pulse request input. Should be connected to the InnoMux REQ output.
GROUND (GND) Pin (Pins 2 & 3)
All ground pins should be connected to secondary ground.
ACKNOWLEDGE (ACK) Pin (Pin 4)
Acknowledge to InnoMux that a request has been issued to the
primary-side. Should be connected to the InnoMux ACK input.
FORWARD COMPARATOR (FWC) Pin (Pin 5)
Forward comparator output to InnoMux. Should be connected to the
InnoMux FWC input.
SECONDARY BYPASS (BPS) Pin (Pin 6)
Supply pin for InnoSwitch3-MX. Must connect to BYPASS pin of
InnoMux controller.
SYNCHRONOUS RECTIFIER DRIVE (SR) Pin (Pin 7)
SR drive output for synchronous rectifier. Should also be connected
to InnoMux SR input.
OUTPUT VOLTAGE (VOUT) Pin (Pin 8)
Should be connected to VCV1 output.
FORWARD (FW) Pin (Pin 9)
Switching node of transformer for sensing.
NOT CONNECTED (NC) Pins (Pins 10, 11, and 12)
These pins are not connected and should be left floating.
UNDER/OVER INPUT VOLTAGE (V) Pin (Pin 13)
Input voltage sense.
PRIMARY BYPASS (BPP) Pin (Pin 14)
Internal voltage supply for primary-side controller.
NOT CONNECTED (NC) Pin (Pin 15)
This pin is not connected and should be left floating.
SOURCE (S) (Pins 16-19)
Internal power switch source connection.
DRAIN (D) (Pin 24)
High-voltage drain connection to internal power switch.
V 13
BPP 14
NC 15
S 16-19
D 24
12 NC
11 NC
10 NC
9 FW
8 VOUT
7 SR
6 BPS
5 FWC
4 ACK
3 GND
2 GND
1 REQ
PI-8311-051717
Figure 6.
InnoSwitch3-MX Pin Configuration.
4
Rev. D 03/20
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InnoSwitch3-MX
InnoSwitch3-MX Functional Description
The InnoSwitch3-MX combines a high-voltage power switch,
along
with both primary-side and secondary-side controllers in one device.
The InnoSwitch3-MX is intended to be paired with an InnoMux
controller.
The InnoSwitch3-MX architecture incorporates a novel inductive
coupling feedback scheme using the package leadframe and bond
wires to provide a safe, reliable, and low-cost means to accurately
communicate power requests from the InnoMux controller to the
primary controller.
The primary controller on InnoSwitch3-MX is a quasi-resonant (QR)
flyback controller that has the ability to operate in continuous
conduction mode (CCM). The controller uses a variable current
control scheme. The primary consists of a jitter oscillator; a receiver
circuit magnetically coupled to the secondary controller, a current
limit controller, 5 V regulator on the PRIMARY BYPASS pin, audible
noise reduction engine, bypass overvoltage detection circuit, a
lossless input line sensing circuit, current limit selection circuitry,
overvoltage protection, leading edge blanking, secondary output
diode / SR MOSFET short protection circuit and a 650 V / 725 V /
750 V power switch.
The secondary controller consists of a transmitter circuit that is
magnetically coupled to the primary receiver, synchronous rectifier
(SR) MOSFET driver, timing functions and a host of integrated
protection features.
Figures 4 and 5 show the functional block diagrams of the primary
and secondary controllers with the most important features.
Primary Controller
InnoSwitch3-MX has variable frequency QR controller plus CCM/CrM/
DCM operation for enhanced efficiency and extended output power
capability.
PRIMARY BYPASS Pin Regulator
The PRIMARY BYPASS pin has an internal regulator that charges the
PRIMARY BYPASS pin capacitor to V
BPP
by drawing current from the
DRAIN pin whenever the power switch is off. The PRIMARY BYPASS
pin is the internal supply voltage node. When the power switch is on,
the device operates from the energy stored in the PRIMARY BYPASS
pin capacitor.
In addition, a shunt regulator clamps the PRIMARY BYPASS pin
voltage to V
SHUNT
when current is provided to the PRIMARY BYPASS
pin through an external resistor. This allows the InnoSwitch3-MX to
be powered externally through a bias winding, decreasing the
no-load consumption and allowing meeting typical TV/Display
application stand-by power requirements of 275 mW input power with
100 mW output load.
Primary Bypass ILIM Programming
InnoSwitch3-MX ICs allow the user to adjust primary current limit
(I
LIM
) settings through the selection of the PRIMARY BYPASS pin
capacitor value. A ceramic capacitor can be used. There are 2
selectable capacitor sizes − 0.47
µF
and 4.7
µF
for setting standard
and increased ILIM settings respectively. More information on which
InnoSwitch3-MX support the adjustable current limit can be found in
the parameters table.
Primary Bypass Undervoltage Threshold
The PRIMARY BYPASS pin undervoltage circuitry disables the power
switch when the PRIMARY BYPASS pin voltage drops below ~4.5 V
(=V
BPP
- V
BPP(H)
) in steady-state operation. Once the PRIMARY BYPASS
pin voltage falls below this threshold, it must rise to V
BPP(SHUNT)
to
re-enable turn-on of the power switch.
Primary Bypass Output Overvoltage Function
The PRIMARY BYPASS pin has an OV protection feature with either a
latching or an auto-reset response. A Zener diode in parallel with the
resistor in series with the PRIMARY BYPASS pin capacitor is typically
used to detect an overvoltage on the primary bias winding and
activate the protection mechanism. In the event that the current into
the PRIMARY BYPASS pin exceeds I
SD
, the device will latch-off or
disable the power switch for a time t
AR(OFF)
, after which time the
controller will restart and attempt to return to regulation.
Output OV protection is also included as an integrated feature on the
InnoMux controller.
Over-Temperature Protection
The thermal shutdown circuitry senses the primary switch die
temperature. The threshold is set to T
SD
with either a hysteretic or
latch-off response.
Hysteretic response: If the die temperature rises above the threshold,
the power switch is disabled and remains disabled until the die
temperature falls by T
SD(H)
at which point switching is re-enabled. A
large amount of hysteresis is provided to prevent over-heating of the
PCB due to a continuous fault condition.
Latch-off response: If the die temperature rises above the threshold
the power switch is disabled. The latching condition is reset by
bringing the PRIMARY BYPASS pin below V
BPP(RESET)
or by going below
the UNDER/OVER INPUT VOLTAGE pin UV (I
UV-
) threshold.
Over-temperature protection is also included as an integrated feature
on the InnoMux controller.
Current Limit Operation
The primary-side controller has a current limit threshold ramp that is
inversely proportional to the time from the end of the previous
primary switching cycle (i.e. from the time the primary switch turns
off at the end of a switching cycle).
This characteristic produces a primary current limit that increases as
the switching frequency (load) increases (Figure 7).
This algorithm enables the most efficient use of the primary switch
with the benefit that this algorithm responds to digital feedback
information immediately when a feedback switching cycle request is
received.
At high load, switching cycles have a maximum current approaching
100% I
LIM
. This gradually reduces to 30% of the full current limit as
load decreases. Once 30% current limit is reached, there is no
further reduction in current limit (since this is low enough to avoid
audible noise). The time between switching cycles will continue to
increase as load reduces.
Jitter
The normalized current limit is modulated between 100% and 95% at
a modulation frequency of f
M
; this results in a frequency jitter of
~7 kHz with average frequency of ~100 kHz.
Auto-Restart
In the event a fault condition occurs (such as an output overload,
output short-circuit, or external component/pin fault), the
InnoSwitch3-MX enters auto-restart (AR) or latches off. This is
typically initiated by the InnoMux controller.
The latching condition is reset by bringing the PRIMARY BYPASS pin
below ~3 V or by going below the UNDER/OVER INPUT VOLTAGE pin
UV (I
UV-
) threshold.
5
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Rev. D 03/20
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