UCC2897A_15 Datasheet, PDF (1/46 Pages) Texas Instruments – Advanced Current-Mode Active-Clamp PWM Controller

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UCC2897A
SLUS829E – AUGUST 2008 – REVISED APRIL 2015
UCC2897A Advanced Current-Mode Active-Clamp PWM Controller
1 Features
•1 Low-Output Jitter
• Soft-Stop Shutdown of MAIN and AUX
• 110-V Input Startup Function
• Ideal for Active-Clamp, Reset-Forward, Flyback
and Synchronous Rectifier Uses
• Provides Complementary Auxiliary Driver with
Programmable Dead Time (Turn-On Delay)
between AUX and MAIN Switches
• Peak Current-Mode Control with 0.5-V Cycle-by-
Cycle Current Limiting
• TrueDrive™ 2-A Sink, 2-A Source Outputs
• Trimmed Internal-Bandgap Reference for
Accurate Line UV and Line OV Threshold
• Programmable Slope Compensation
• High-Performance 1-MHz Synchronizable
Oscillator with Internal Timing Capacitor
• Precise Programmable Maximum Duty Cycle
• PB-Free Lead Finish Package
2 Applications
• High-Efficiency DC-to-DC Power Supplies
• Server Power, 48-V Telecom, Datacom, and 42-V
Automotive Applications
3 Description
The UCC2897A PWM controller simplifies
implementation of the various active clamp or reset
and synchronous rectifier switching power topologies.
The UCC2897A is a peak current-mode fixed-
frequency high-performance pulse-width modulator.
The controller includes the logic and the drive
capability for the P-channel auxiliary switch along with
a simple method of programming the critical delays
for proper active-clamp operation.
Features include an internal programmable slope
compensation circuit, precise D_MAX limit, and a
synchronizable oscillator with an internal-timing
capacitor. An accurate line-monitoring function also
programs the ON and OFF transitions of the
converter with regard to the bulk input voltage, VIN.
The UCC2897A adds a second-level hiccup-mode
current-sense
threshold,
bi-directional
synchronization and input-overvoltage protection
functionalities. The UCC2897A is offered in 20-pin
TSSOP (PW) and 20-pin QFN (RGP) packages.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
UCC2897A
TSSOP (20)
VQFN (20)
6.60 mm x 6.60 mm
4.15 mm x 4.15 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Typical Application Diagram
R_DEL
UCC2897A
3 RDEL
VIN 1
BIAS
WINDING
+VIN
R_ON
R_OFF
C_VREF
C_F
R_SLOPE
LINEOV 19
4 RTON
LINEUV 18
5 RTOFF
VDD 17
6 VREF
C_BIAS
PVDD 16
7 SYNC
R_OUT
15
8 GND
OUT
C_AUX
D_AUX
9 CS
AUX 14
10 RSLOPE PGND 13
Q1
D1
Q2
12 SS/SD
FB 11
C_SS
Q4
D3
L_O
D4 _CO
Q3
SR
DRIVE
SECONDARY
SIDE E/A
LOAD
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.