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MAX17691A/MAX17691B
4.2V–60V No-Opto Isolated
Flyback Converter with Integrated FET
General Description
Benefits and Features
Maxim's Rainier family of isolated power devices enable
cooler, smaller, and simpler power-supply solutions. The
MAX17691A/B is a high efficiency No-Opto integrated
nMOSFET flyback converter that uses fixed frequency
peak current mode control. The device senses the isolated
output voltage directly from the primary-side flyback wave-
form during secondary-side rectifier conduction. No sec-
ondary-side error amplifier and optocoupler are required
to provide an accurate, isolated, regulated output voltage,
saving up to 20% of PCB space normally required for a
traditional flyback converter.
● Reduces External Components and Total Cost
• Eliminates the Optocoupler and Secondary-Side
Error Amplifier
• Up to 20% Space Savings
• 76V, Low R
Integrated nMOSFET
DSON
• Internal Loop Compensation (MAX17691A)
• Built-In Soft-Start
● Reduces Power Dissipation
• > 90% Efficiency
• Delivers up to 7.5W Output Power
• Frequency Fold-Back Enables Enhanced Light-
Load Efficiency
The MAX17691A/B features a low R
, 76V, 170mΩ
DSON
integrated nMOSFET primary switch and is designed to
operate over a wide supply range from 4.2V to 60V. The
switching frequency of the device is programmable from
100kHz to 350kHz. An EN/UVLO feature allows the user
to turn ON/OFF the power converter precisely at the de-
sired input voltage. Input overvoltage protection can be
implemented using the OVI pin (MAX17691A only). Soft-
start limits inrush current at startup. The MAX17691A/B
supports external clock synchronization to avoid low-fre-
quency “beats” on the input bus in systems with multiple
converters. The device also has programmable frequency
dithering for low-EMI, spread-spectrum operation.
• 2.5µA Shutdown Current
● Supports Key System-Level Design Requirements
• Frequency Dithering Supports Low-EMI, Spread-
Spectrum Operation
• Switching Frequency Synchronization to External
Clock
• Compliant with CISPR22 ClassB EMI Requirements
● Operates Reliably in Adverse Environments
• Output Diode Forward Voltage Temperature
Compensation
• Hiccup Current-Limit Protection
• Programmable EN/UVLO Threshold
• Input Overvoltage (OVI) Protection (MAX17691A)
• Overtemperature Protection
• High Industrial -40°C to +125°C Ambient Operating
Temperature Range/ -40°C to +150°C Junction
Temperature Range
The MAX17691A/B allows temperature compensation for
variations in the output rectifier diode forward voltage
drop. The MAX17691A is internally compensated for loop
stability, while the MAX17691B offers external loop com-
pensation flexibility. The MAX17691A/B has robust hic-
cup-protection and thermal protection schemes, and is
available in a space-saving 12-pin, 3mm x 3mm TDFN
package with a temperature range from -40°C to +125°C.
Ordering Information appears at end of data sheet.
Applications
● Isolated Power Supplies
● PLC I/O Modules
● IGBT Gate Drive Supplies
● Industrial and Telecom Applications
19-100784; Rev 1; 2/21