UCC28730-Q1 Datasheet, PDF (9/42 Pages) Texas Instruments – Zero-Power Standby PSR Flyback Controller for Automotive

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7 Detailed Description
UCC28730-Q1
SLUSCR9 – JUNE 2017
7.1 Overview
The UCC28730-Q1 is an isolated-flyback power supply controller which provides accurate voltage and constant
current regulation using primary-side winding sensing, eliminating the need for opto-coupler feedback circuits.
The controller operates in discontinuous conduction mode with valley switching to minimize switching losses. The
modulation scheme is a combination of frequency modulation and primary peak-current modulation to provide
high conversion efficiency across the load range. The control law provides a wide dynamic operating range of
output power which facilitates the achievement of <5-mW stand-by power.
During low-power operating levels the device has power management features to reduce the device operating
current at switching frequencies less than 28 kHz. The UCC28730-Q1 includes features in the pulse-width
modulator to reduce the EMI peak energy at the fundamental switching frequency and its harmonics. Accurate
voltage and current regulation, fast dynamic response, and fault protection are achieved with primary-side
control. A complete charger solution can be realized with a straightforward design process, low cost, and low
component-count.
7.2 Functional Block Diagram
VDD 1
I_HV
7 HV
GND 4
VS 2
CBC 3
UVLO
21 V / 7.7 V
WAKE SIGNAL
DETECTION
WAKE
POWER
& FAULT
MANAGEMENT
INTERNAL
BIAS
WAIT
OC FAULT
OV FAULT
LINE UVLO
4.04 V + VCVS +
E/A
VCL
CONTROL
LAW
SAMPLER
VALLEY
SWITCHING
+
VOVP
OV FAULT
1 / fSW
VCST
14.5 V
SQ
SECONDARY
TIMING
DETECT
CURRENT
REGULATION
RQ
LEB
VCVS
= ICBC
x 3 kÈ
ICBC
CABLE
COMPENSATION
28 kÖ
+
0 V to VCBC(max)
VDD
29 mA
6 DRV
+
VCST
5 CS
IVSLS
LINE
SENSE
IVSLS
10 kÖ
+
2.25 V / 0.8 V
LINE UVLO
IVSLS / KLC
OC FAULT
+
1.5 V
Copyright © 2017, Texas Instruments Incorporated
Copyright © 2017, Texas Instruments Incorporated
Product Folder Links: UCC28730-Q1
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