UC1842A-SP_16 Datasheet, PDF (1/31 Pages) Texas Instruments – QML Class V, Current-Mode PWM Controller

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UC1842A-SP, UC1843A-SP, UC1844A-SP
SLUS872D – JANUARY 2009 – REVISED MAY 2015
UC184xA-SP QML Class V, Current-Mode PWM Controller
1 Features
•1 QML Class V (QMLV) Qualified, SMD 5962-86704
• Rad-Tolerant: 30 kRad (Si) TID ^{(1) (2)}
• Optimized for Offline and DC-to-DC Converters
• Low Start-Up Current (<0.5 mA)
• Trimmed Oscillator Discharge Current
• Automatic Feed Forward Compensation
• Pulse-by-Pulse Current Limiting
• Enhanced Load Response Characteristics
• Undervoltage Lockout (UVLO) With Hysteresis
• Double-Pulse Suppression
• High-Current Totem-Pole Output
• Internally-Trimmed Bandgap Reference
• 500-kHz Operation
• Low R_O Error Amplifier
(1) The LDR improved die is only available in the UC1843A-SP
(orderable as 5962-8670409VPA). Contact factory to request
an LDR-improved version of the UC1842A-SP or UC1844A-
SP.
(2) Radiation tolerance is a typical value based upon initial device
qualification with dose rate = 10 mrad/s. Radiation lot
acceptance testing is available - contact factory for details.
2 Applications
• DC-DC Converters
• Supports Various Topologies:
– Flyback, Forward, Buck, Boost
– Push-Pull, Half-Bridge, Full Bridge With
External Interface Circuit
• Available in Military Temperature Range (–55°C to
125°C)
3 Description
The UC184xA family of control ICs is a pin-for-pin
compatible improved version of the UC184x family.
Providing the necessary features to control current-
mode switched-mode power supplies, this device has
the following improved features. Start up current is
specified to be less than 0.5 mA. Oscillator discharge
is trimmed to 8.3 mA. During UVLO, the output stage
can sink at least 10 mA at less than 1.2 V for V_CC
over 5 V.
The Device Comparison Table shows the difference
between members of this family. Reference the
individual product data sheets for ordering the
radiation-improved version if available.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
UC1842A-SP
UC1843A-SP
UC1844A-SP
CDIP (8)
LCCC (20)
6.67 mm × 9.60 mm
8.89 mm × 8.89 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
4 Simplified Schematic
V_CC 7
Gnd 5
R_T/C_{T 4}
V_{FB 2}
Comp 1
C/S ³
34 V
UVLO
S/R
5-V
REF
2.5 V
Osc
Error
Amplifier
V_REF
Good
Logic
Internal
Bias
2R
S
R
1V
R
PWM
Latch
Current
Sense
Comparator
8 _VREF
5.0 V
50 mA
7 V_C
6 Output
5 _Pwr
Ground
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.