UCC2752 Datasheet, PDF (1/6 Pages) Texas Instruments – Resonant Ring Generator Controller

UCC2752
UCC3752
Resonant Ring Generator Controller
PRELIMINARY
FEATURES
• Novel Topology for Low-Cost, Efficient
Generation of Ring Voltage
• Suitable for Multi-Line Operation
• Selectable 20, 25 and 50 Hz Ring
Frequency
DESCRIPTION
The UCC3752 controller is designed for driving a power stage that gener-
ates low frequency, high voltage sinusoidal signals for telephone ringing
applications. The controller and the power stage are most suitable for up to
5 line applications where low cost, high efficiency and minimum parts count
are critical. A semi-regulated DC voltage is added as an offset to the ring-
ing signal. The ring generator operation is non-isolated and open loop.
• Secondary (AC) Current Limiting
Generates an Off-Hook Detect Signal
• Primary Current Limiting to Turn
Power Stage Off Under Fault
Conditions
• Operates from a Single 12V Supply
The UCC3752 directly drives primary side switches used to implement a
push-pull resonant converter topology and transformer coupled sampling
switches located on the secondary of the converter. For normal ring signal
generation, the primary switching frequency and secondary sampling fre-
quency are precisely offset from each other by the ringing frequency to pro-
duce a high voltage low frequency alias signal at the output. The off-hook
condition is detected by sensing the AC current and when AC limit is ex-
ceeded, a flag is generated on the OFFHOOK pin.
The drive signal frequencies are derived from a high frequency (3579545
Hz) crystal. The primary switching frequency is 89.489 kHz and the sam-
pling frequency is 20, 25 or 50 Hz less depending on the status of fre-
quency select pins FS0 and FS1.
The circuits described in this datasheet are covered under US Patent #5,663,878 and other patents pending.
TYPICAL APPLICATION
L_IN
T1
V_IN
12V
L_R
L_R
12V
N:1
C_R1
Q1
D1
R_SENSE
C_DC
C_R2
SAMPLING
CIRCUIT
DC SIGNAL
V₁
AC SIGNAL
C_F
V_OUT
C_BYP1
9
VS12
11 DRV1
5 DCLIM
12
2
DRVS
N/C
6
OHD
4
VDD
UCC3752
ENABLE 10
OFFHOOK 1
C_BYP2
Q2
13 DRV2
XTAL2 15
GND
PGND
FS0
FS1
XTAL1
3
14
7
8
16
SLUS269 - JULY 1999
3.579545MHz
UDG-98058