Texas Instruments UCC3751N, UCC3751DTR, UCC3751D, UCC2751N, UCC2751DTR Datasheet

Single Line Ring Generator Controller

UCC2751

UCC3751

PRELIMINARY

FEATURES

•Novel Topology for Low-Cost, Efficient Generation of Ring Voltage

•Provides DC Offset and “Talk Battery” Voltage for Off-Hook Conditions

•Selectable 20, 25 and 50 Hz Ring Frequency

•Secondary (AC) Current Limiting Allows Removal of AC Voltage under Off-Hook Conditions

•Primary Current Limiting to turn Power Stage off under Fault Conditions

•Operates from a Single 12V Supply

DESCRIPTION

The UCC3751 controller is designed for driving a power stage that generates low frequency, high voltage sinusoidal signals for telephone ringing applications. The controller and the power stage are most suitable for single line applications where low cost, high efficiency and minimum parts count are critical. In addition to providing the sinusoidal ringing signal, the controller and the power stage are designed to provide the required DC voltage across the output when the phone goes off-hook. The DC voltage is also added as the offset to the ringing signal. This feature eliminates the need to have a separate talk battery voltage power supply as well as relays and drivers to switch between the ringing voltage and the talk battery.

The UCC3751 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 frequency are precisely offset from each other by the ringing frequency to produce 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 exceeded, the sampling frequency is set to be equal to the primary switching frequency to produce a DC output.

The drive signal frequencies are derived from a high frequency (3579545 Hz) crystal. The primary switching frequency is 89.488 kHz and the sampling frequency is 20, 25 or 50 Hz less depending on the status of frequency select pins FS0 and FS1.

The circuits described in this datasheet are covered under US Patent #5,663,878 and other patents pending.

TYPICAL APPLICATIONS CIRCUIT

					D1			RSENSE
LIN		T1				CDC		DC SIGNAL
VIN
12V									V1
	L	R		CR2				AC SIGNAL	CF
					SAMPLING				VOUT
					CIRCUIT
	LR		12V
CR1		N:1	CBYP1	9	12	2	6	4
									CBYP2
				VS12	DRVS	RINGEN	OHD	VDD
	Q1		11	DRV1				ENABLE	10
			5	DCLIM		UCC3751		DELAY	1
Q2			13	DRV2				XTAL2	15
				GND	PGND	FS0	FS1	XTAL1
				3	14	7	8	16
									UDG-98047
								3.579545MHz
SLUS267A - JULY 1999

ABSOLUTE MAXIMUM RATINGS

Input Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V Analog Inputs (OHD, DCLIM, XTAL1, XTAL2)

Maximum Forced Voltage. . . . . . . . . . . . . . . . . . . . –0.3 to 5V Logic Inputs

Maximum Forced Voltage . . . . . . . . . . . . . . . . . . –0.3 to 7.5V Reference Output Current (VDD) . . . . . . . . . . . Internally Limited Output Current (DRV1, DRV2, DRVS) Pulsed . . . . . . . . . . 1.5A Operating Junction Temperature . . . . . . . . . . –55°C to +125°C Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C

Note: Unless otherwise indicated, voltages are referenced to ground and currents are positive into, negative out of, the specific terminals. Pulsed is defined as a less than 10% duty cycle with a maximum duration of 500 S.

UCC2751

UCC3751

CONNECTION DIAGRAM

DIL-16, SOIC-16 (TOP VIEW)

N or D Packages

DELAY	1	16	XTAL1
RINGEN	2	15	XTAL2
GND	3	14	PGND
VDD	4	13	DRV2
DCLIM	5	12	DRVS
OHD	6	11	DRV1
FS0	7	10	ENABLE
FS1	8	9	VS12

BLOCK DIAGRAM

ENABLE	10
XTAL2	15
		MODULO	MODULO
XTAL1	16	20	2
		COUNTER	COUNTER
							11	DRV1
		ONE-SHOT
DCLIM	5						13	DRV2
		300mV	PROGRAMMABLE
			COUNTER	CLR
				CLK
							12	DRVS
DELAY	1		2 BIT			ONE-SHOT
			A/D
OHD	6
		300mV					14	PGND
						1/FOSC
RINGEN	2	MODULO
		1,800
				2/FOSC	MODULO
		COUNTER					3	GND
					40
FS1	8				COUNTER
		MODULO
		3,560					9	VS12
		COUNTER		ONE-SHOT
FS0	7						5 VOLT
							REFERENCE
		MODULO					4	VDD
		4,480
		COUNTER
							4.5V
							UDG-98020
					2

Table I. Frequency selectability decoding.

FS1	FS0	MODE	Sine Wave
			Frequency (Hz)
0	0	1	20
0	1	1	25
1	0	1	50
1	1	3	0
OHD = 0.5		2	0

					UCC2751
					UCC3751
RINGEN	OHD	FS1	FS0	FDRVS		FDRV–
						FDRVS
1	0	0	0	89.469kHz		20Hz
1	0	0	1	89.464kHz		25Hz
1	0	1	0	89.439kHz		50Hz
0	X	X	X	89.489kHz		0.0Hz
X	1	X	X	89.489kHz		0.0Hz

ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications hold for TA = 0°C to 70°C for the UCC3751 and –40°C to +85°C for the UCC2751, T A = TJ.

PARAMETER	TEST CONDITIONS	MIN	TYP	MAX	UNITS
V12 Supply Current Section
Supply Current	ENABLE = 0V		0.5	3.0	mA
	ENABLE = 5V		0.5	3.0	mA
Internal Reference with External Bypass Section
Output Voltage (VDD)		4.85	5	5.15	V
Load Regulation	0mA ≤ IVDD ≤ 2mA		5		mV
Line Regulation	10V < VS12 < 13V, IVDD = 1mA		3		mV
Short Circuit Current	VDD = 0	5	10		mA
Output Drivers Section (DRV1, DRV2)
Pull Up Resistance	ILOAD = 10mA to 20mA		6	15	Ω
Pull Down Resistance	ILOAD = 10mA to 20mA		6	15	Ω
Rise Time	CLOAD = 1nF		50	100	nS
Fall Time	CLOAD = 1nF		50	100	nS
Output Drivers Section (DRVS)
Pull Up Resistance	ILOAD = 10mA to 20mA		4	10	Ω
Pull Down Resistance	ILOAD = 10mA to 20mA		4	10	Ω
Sample Pulse-Width	Mode 1 and 2, (Note 1)		280		nS
Rise Time	CLOAD = 1nF		50	100	nS
Fall Time	CLOAD = 1nF		50	100	nS
Current Limit Section
OHD Threshold			300		mV
OHD Input Current	VOHD = 0V		–100		nA
DCLIM Threshold			300		mV
DCLIM Input Current	VDCLIM = 0V		–100		nA
Frequency Section (Note 1)
Primary Switching Frequency	All cases 3.579545 MHz Crystal		89489		Hz
Sampling Switching Frequency	FS0 = 0, FS1 = 0, Mode 1, (Note 1)		89469		Hz
	FS0 = 1, FS1 = 0, Mode 1		89464		Hz
	FS0 = 0, FS1 = 1, Mode 1		89439		Hz

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