The UC1842/3/4/5 family of control devices provides the necessary features to implement off-line or dc-to-dc fixed frequency current mode control schemes with a minimal external parts count

UC2845

Manufacturer Part NumberUC2845
DescriptionThe UC1842/3/4/5 family of control devices provides the necessary features to implement off-line or dc-to-dc fixed frequency current mode control schemes with a minimal external parts count
ManufacturerTexas Instruments
UC2845 datasheet
 


Specifications of UC2845

TopologyBoost, Flyback, ForwardControl MethodCurrent
Duty Cycle(max)(%)50Frequency(max)(khz)450
Uvlo Thresholds On/off(v)8.4/7.6Pin/package14SOIC, 8PDIP, 8SOIC
Vin(min)(v)7.6Vin(max)(v)30
Regulated Outputs(#)1Operating Temperature Range(c)-40 to 85
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ERROR AMP CONFIGURATION
Error amp can source or sink up to 0.5 mA.
Z
I
UNDER-VOLTAGE LOCKOUT
During under-voltage lock-out, the output drive is biased to sink minor amounts of current. Pin 6 should be
shunted to ground with a bleeder resistor to prevent activating the power switch with extraneous leakage
currents.
V
7
ON/OFF Command
CC
to REST of IC
UC1842
UC1844
V
16 V
ON
V
10 V
OFF
CURRENT SENSE CIRCUIT
A small RC filter may be required to suppress switch transients.
I
S
R
C
R
S
5
2.5 V
+
V
FB
_
2
COMP
Z
1
F
V
CC
UC1843
<17 mA
UC1845
8.4 V
7.6 V
<1 mA
ERROR
AMP
2R
R
COMP
1
CURRENT
3
SENSE
GND
5
Peak Current (I
) is Determined By The Formula
S
,1.0 V
I
SMAX
RS
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UC1842/3/4/5
UC2842/3/4/5
UC3842/3/4/5
SLUS223C – APRIL 1997 – REVISED JUNE 2007
0.5 mA
V
CC
V
V
OFF
ON
1 V
CURRENT
SENSE
COMPARATOR
5