Si8281/82/83/84 Data Sheet
ISODrivers with Integrated DC-DC Converters
KEY FEATURES
The Si828x family (Si8281/82/83/84) is made up of isolated, high-current gate drivers
with integrated system safety and feedback functions. These devices are ideal for driving
power MOSFETs and IGBTs used in a wide variety of inverter and motor control applica-
tions. The Si828x isolated gate drivers utilize Silicon Labs' proprietary silicon isolation
technology, supporting up to 5.0 kVrms withstand voltage per UL1577. This technology
enables higher-performance, reduced variation with temperature and age, tighter part-to-
part matching, and superior common-mode rejection compared to other isolated gate
driver technologies.
In addition to the gate driver, the Si828x family integrates a dc-dc controller for simple
implementation of an isolated supply for the driver side. The Si828x dc-dc controller can
be ordered in two different configurations depending on what system voltage rails are
available and the amount of power needed. The Si8281 and Si8283 have integrated
power switch but are limited in dc-dc voltage input to the device bias. The Si8282 and
Si8284 utilize and external power switch and are able to accept much higher voltage in-
put power rail. User-adjustable frequency for minimizing emissions, a soft-start function
for safety, and a shut-down option are available options. The device requires only mini-
mal passive components and a miniature transformer.
The input to the device is a complementary digital input that can be utilized in several
configurations. The input side of the isolation also has several control and feedback digi-
tal signals. The controller to the device receives information about the driver side power
state and fault state of the device and recovers the device from fault through an active-
low reset pin.
On the output side, Si828x devices provide separate pull-up and pull-down pins for the
gate. A dedicated DSAT pin detects the desaturation condition and immediately shuts
down the driver in a controlled manner. The Si828x devices also integrate a Miller clamp
to facilitate a strong turn-off of the power switch.
Applications
• IGBT/ MOSFET gate drives
• Industrial, HEV, and renewable energy inverters
• AC, Brushless, and DC motor controls and drives
• Variable-speed motor controllers
• Isolated switch mode and UPS power supplies
Safety Regulatory Approvals (Pending)
• UL 1577 recognized
• Up to 5000 V
RMS
for 1 minute
• CSA component notice 5A approval
• IEC 60950-1 (reinforced insulation)
• VDE certification conformity
• VDE0884 Part 10 (basic insulation)
• CQC certification approval
• GB4943.1 (reinforced insulation)
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• System Safety Features
• DESAT detection
• FAULT feedback
• Undervoltage Lock Out (UVLO)
• Soft shutdown on fault condition
• Silicon Labs’ high-performance isolation
technology
• Industry leading noise immunity
• High speed, low latency and skew
• Best reliability available
• 30 V driver-side supply voltage
• Integrated Miller clamp
• Power ready pin
• Complementary driver control input
• Compact packages: 20 and 24-pin wide-
body SOIC
• Integrated DC-DC converter
• Feedback-controlled converter with
dithering for low EMI
• DC-DC converter efficiency of 83%
• Shutdown, frequency, and soft-start
controls
• Industrial temp range: –40 to 125 °C
Rev. 1.0
Table of Contents
1. Ordering Guide
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Isolation Channel Description
2.2 Device Behavior .
2.3 Input .
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. 5
. 5
. 6
. 6
. 6
. 6
. 6
. 6
. 7
. 7
. 8
. 9
. 9
. 9
. 9
.10
.10
.10
.10
.10
.11
.12
.13
2.4 Driver Side Output .
2.5 Fault (FLTb) Pin .
2.6 Reset (RSTb) Pin.
2.7 Ready (RDY) Pin .
2.8 Undervoltage Lockout (UVLO) .
2.9 Desaturation Detection .
2.10 Soft Shutdown .
2.11 Miller Clamp .
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2.12 DC-DC Converter Application Information . . . . . .
2.12.1 External Transformer Driver. . . . . . . . .
2.12.2 Output Voltage Control . . . . . . . . . .
2.12.3 Compensation . . . . . . . . . . . . .
2.12.4 Thermal Protection. . . . . . . . . . . .
2.12.5 Cycle Skipping . . . . . . . . . . . . .
2.12.6 Shutdown (Si8283 and Si8284 Only). . . . . .
2.12.7 Soft Start (Si8283 and Si8284 Only) . . . . . .
2.12.8 Programmable Frequency (Si8283 and Si8284 Only)
2.12.9 Low Supply Voltage Configuration . . . . . .
2.12.10 High Supply Voltage Configuration . . . . . .
2.13 Transformer Design
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3. Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 Recommended Application Circuits.
3.1.1 Inputs . . . . . . . .
3.1.2 Reset, RDY, and Fault . . .
3.1.3 Desaturation . . . . . .
3.1.4 Driver Outputs. . . . . .
3.2 Layout Considerations .
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3.3 Power Dissipation Considerations .
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.14
.15
.16
.16
.16
.16
.17
4. Electrical Specifications
4.1 Timing Diagrams .
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. . . . . . . . . . . . . . . . . . . . . . . . . . 20
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.26
.27
.31
4.2 Typical Operating Characteristics .
4.3 Regulatory Information .
5. Pin Descriptions
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Rev. 1.0 | 2
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Si8281/82/83/84 Data Sheet
System Overview
2. System Overview
2.1 Isolation Channel Description
The operation of an Si828x channel is analogous to that of an optocoupler and gate driver, except an RF carrier is modulated instead of
light. This simple architecture provides a robust isolated data path and requires no special considerations or initialization at start-up. A
simplified block diagram for a single Si828x channel is shown in the figure below.
Transmitter
RF
OSCILLATOR
Receiver
V
DD
Semiconductor-
Based Isolation
Barrier
DEMODULATOR
+
NOISE FILTER
A
Input
Logic
V
H
V
L
Gnd
MODULATOR
Figure 2.1. Simplified Channel Diagram
A channel consists of an RF Transmitter and RF Receiver separated by a semiconductor-based isolation barrier. Referring to the
Transmitter, input A modulates the carrier provided by an RF oscillator using on/off keying. The Receiver contains a demodulator that
decodes the input state according to its RF energy content and applies the result to output B via the output driver. This RF on/off keying
scheme is superior to pulse code schemes as it provides best-in-class noise immunity, low power consumption, and better immunity to
magnetic fields.
2.2 Device Behavior
The following table shows state relationships for the Si828x inputs and outputs.
Table 2.1. Si8281/82/83/84 Truth Table
VDDB–VMID
State
Powered
Powered
Powered
Unpowered
Powered
Desaturation
State
Undetected
Undetected
Undetected
—
Detected
IN+
H
H
L
X
X
IN–
H
L
X
X
X
VDDA State
Powered
Powered
Powered
Powered
Powered
VH
Hi-Z
Pull-up
Hi-Z
—
Hi-Z
VL
Pull-down
Hi-Z
Pull-down
—
Pull-down
1
RDY
H
H
H
L
H
FLTb
H
H
H
H
L
Note:
1. Driver state after soft shutdown.
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Rev. 1.0 | 5
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