TK75002 Datasheet, PDF (1/10 Pages) TOKO, Inc – ERROR SIGNAL ISOLATOR

TK75002
ERROR SIGNAL ISOLATOR
FEATURES
s Eliminates Opto-coupler from Feedback Loop
s Replaces TL431 and Eliminates Parasitic Zero
s Pulse Transformer Driver
s Same Transformer for Any Output Voltage
s Peak Current Controlled
s Automatic Volt-Second Balancing
s Self-running Oscillator
s Hi-performance Op-amp & Bandgap Reference
s Functionally Integrated & Simplified 5-pin Design
APPLICATIONS
s Power Supplies with Primary-Side Controller
s Low Isolation-Barrier Capacitance Equipment
s Instrumentation
s Industrial Process Control
s Test Equipment
s Data Acquisition
DESCRIPTION
The TK75002 monitors the output voltage of a power
supply, generates an error signal, and transmits the error
signal across an isolation barrier using a small pulse
transformer. In conjunction with the pulse transformer, it
replaces the TL431/opto-coupler combination and
eliminates the undesirable zero created in the feedback
loop by that combination. The transformer is driven with
pulse amplitude modulation in a free-running oscillator
configuration. The period of oscillation is proportional to
the inductance of the pulse transformer. The magnitude of
the voltage pulse is internally limited so that the pulse
transformer design need not be changed for various output
voltages.
The TK75002 is available in an 8-pin DIP package.
ORDERING INFORMATION
TK75002D
Tape/Reel Code
Temperature Code
EXTENDED TEMP. RANGE
I: -40 TO +85 C
TAPE/REEL CODE
MG: Magazine
TK75002
75002
DRV
GND
NC
INV
VCC
NC
NC
COMP
BLOCK DIAGRAM
VCC
DRV
TRANSFORMER
RESET
DETECTOR
BANDGAP
REFERENCE
650 mV
UVLO
LEVEL SHIFTER
VLS = K(2.5 V - VCOMP)
PAM LATCH
S
Q
BUFFER
R
PEAK
CURRENT
DETECTOR
PAM SWITCH
++
VLS
--
2.5 V
VCOMP
ERROR AMPLIFIER
4Ω
1.35 V
220 mV
COMP
INV
GND
January 1999 TOKO, Inc.
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