SRK1001 rectification controller Datasheet

SRK1001 Datasheet, PDF, Equivalent


Part Number

SRK1001

Description

Adaptive synchronous rectification controller

Manufacture

STMicroelectronics

Total Page 27 Pages
Datasheet
Download SRK1001 Datasheet


SRK1001
SRK1001
Datasheet
Adaptive synchronous rectification controller for flyback converter
SO8 package
Product status link
SRK1001
Product summary
Order code
SRK1001
Package
SO8
Packing
Tape and reel
Features
• Secondary side synchronous rectification controller optimized for flyback
converter
• Suitable for QR and mixed CCM/DCM fixed frequency operation
• Wide VCC operating voltage range 3.7 to 32 V
• CC regulation operation down to 2V output supported
• Very low quiescent current in low consumption mode (170 µA)
• High-voltage sensing input for SR MOSFET drain-source voltage (185 V AMR)
• Operating frequency up to 300 kHz
• High-current gate-drive output for N-MOSFET
• Fast turn-on with minimum delay time and adaptive turn-off logic
• Programmable minimum TON and TOFF
• Low consumption mode entry by DIS pin, by primary side burst-mode detection
or by detection of SR MOSFET conduction lower than programmed min. TON
• SO8 package
Applications
• AC-DC adapters
• Battery chargers / quick chargers
• USB power delivery (profile 4)
• Industrial SMPS
Description
The SRK1001 controller is designed for secondary side synchronous rectification
(SR) in flyback converters, suitable for operation in QR and mixed CCM/DCM fixed
frequency circuits.
It provides a high-current gate-drive output capable of driving N-channel Power
MOSFETs.
The control scheme of this IC is such that the SR MOSFET is switched on as soon as
current starts flowing through its body diode, and then switched off as current
approaches zero.
The fast turn-on with minimum delay and innovative adaptive turn-off logic allow
maximizing the conduction time of the SR MOSFET and eliminating the effect of
parasitic inductance in the circuit.
The device enters low consumption mode when it detects primary controller burst-
mode operation, or when the DIS pin is pulled up by the user, or when the SR
MOSFET conduction falls below the programmed minimum TON. This improves the
converter efficiency at light load, where synchronous rectification is no longer
beneficial.
After the converter restarts switching or the DIS pin goes low again and the IC
detects that the current conduction in the rectifiers has increased 20% above the min
TON programmed value, the IC exits low consumption mode and resumes switching
operation.
DS13155 - Rev 1 - November 2019
For further information contact your local STMicroelectronics sales office.
www.st.com

SRK1001
SRK1001
Block diagram and pin connection
1 Block diagram and pin connection
Figure 1. Internal block diagram
DVS
TON
TOFF
GD
HV CLAMP
COMPARATORS
ON ZCD
ADAPTIVE
CONTROL
TIMER
DRIVER
CONTROL LOGIC
POWER
MANAGEMENT &
SWITCH OVER
GND
Figure 2. Pin connections (top view)
DIS/SYNC
GD
GND
VCC
1
2
3
4
8 TON
7 TOFF
6 VAUX
5 DVS
SO8
DIS/SYNC
VAUX
VCC
Table 1. Pin functions
N. Name
Function
This pin has two functions: disable and synchronization input.
1
DIS/
SYNC •
Asynchronous turn-off of SR MOSFET always occurs after DIS pin voltage shows a positive rising edge
and the synchronous rectification stays disabled as long as it remains at the high level. If the DIS pin
voltage stays high for at least 4 switching cycles, the device enters low consumption mode.
Synchronization function requires that no external capacitor must be mounted between TON pin and GND,
so that SR MOSFET turn-off is accomplished by the positive rising edge of the applied SYNC signal or
when triggered by ZCD comparator output.
This pin is pulled high by internal current source (5 µA); if not used, it must be grounded.
Gate driver output. Totem pole output stage is able to drive power MOSFET with high peak current levels. To
2 GD avoid excessive gate voltages in case the device is supplied with a high VCC, the high level voltage of this pin is
clamped to about 11.5 V. The pin must be connected directly to the SR MOSFET gate terminal.
3
GND
Return of the device bias current and return of the gate drive current. Route this pin close to the source terminal
of synchronous rectifier MOSFET.
DS13155 - Rev 1
page 2/27


Features SRK1001 Datasheet Adaptive synchronous r ectification controller for flyback con verter SO8 package Product status lin k SRK1001 Product summary Order code SRK1001 Package SO8 Packing Tape a nd reel Features • Secondary side sy nchronous rectification controller opti mized for flyback converter • Suitabl e for QR and mixed CCM/DCM fixed freque ncy operation • Wide VCC operating vo ltage range 3.7 to 32 V • CC regulati on operation down to 2V output supporte d • Very low quiescent current in low consumption mode (170 µA) • High-vo ltage sensing input for SR MOSFET drain -source voltage (185 V AMR) • Operati ng frequency up to 300 kHz • High-cur rent gate-drive output for N-MOSFET • Fast turn-on with minimum delay time a nd adaptive turn-off logic • Programm able minimum TON and TOFF • Low consu mption mode entry by DIS pin, by primar y side burst-mode detection or by detec tion of SR MOSFET conduction lower than programmed min. TON • SO8 package Applications • AC-DC adapters • Battery chargers / .
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