2 Phase NECL/TTL Frequency Divider

SKU:

$ 2,633.50

Item	Description
88000102-4	Cable, triple voltage, with modular plugs, Length in ft.
88000103-4	Cable, triple voltage, with modular plug and pig tail leads, Length in ft.

Product Description
Diagrams
Applications
Specifications
Documents

Applications:

System clock simulation
Low-jitter NECL/TTL clock source
SONET clock generator
Low-jitter Laser System Synchronization
Dividing Ti:S laser oscillator signals
A Mini Modular Instrument ™ for working with TTL/CMOS and ECL circuits
The PRL-260BNT replaces the discontinued PRL-260ANT

Features:

f/2 to f/4096, manually programmable
Common divider f/n (2 = n = 256) has 8-bit resolution
Φ1 output=(f/n)/(1, 2, 4 or 8), for max ratio of 2048
Φ2 output=(f/n)/(2, 4, 8 or 16), for max ratio of 4096
Φ1 has complementary NECL& TTL outputs and square wave outputs except when the final divisor is 1
Φ2 has complementary NECL square wave outputs
Single-ended NECL, differential NECL, or AC-coupled sinewave inputs with internal 50 Ω/V_TT terminations
Additional logically-ORed TTL input requires only 0.7 V
Small Signal Comparator Input requires only 40 mV
20 ps typical edge jitter
50 ps typical skew between f/n & f/n NECL outputs
200 ps typical skew between f/n & f/n TTL outputs
1.25 GHz typical max. external clock input frequency
Complementary NECL outputs drive 50 Ω loads terminated to V_TT, AC-coupled or floating 50 Ω loads
Complementary TTL outputs drive long lines with or without 50 Ω load terminations
DC-coupled I/Os
SMA I/O connectors except for TTL/Small Signal Input (BNC)
Ready-to-use 1.3 x 2.9 x 6.1-in. module includes a ±8.5V AC/DC adapter

Description

The PRL-260BNT is a DC-coupled, manually programmable, two-phase frequency divider with two sets of divided outputs, Φ1 and Φ2. It is capable of running at input clock frequencies in excess of 1 GHz and outputting divided TTL and NECL clock signals. The input frequency f is first divided down to f/n, where 2 ≤ n ≤ 256, via D1-D8 of a ten-bit DIP switch. The f/n signal is further divided by 1, 2, 4, or 8 for the Φ1 NECL and TTL outputs via D9 and D10, for a maximum ratio of 2048, and by 2, 4, 8 or 16 for the Φ2 NECL output via D11 and D12 of a second two-bit DIP switch, for a maximum ratio of 4096.

All outputs are synchronous with the input frequency and are square waves (50% duty cycle), except for Φ1 output when the final divisor is set to 1 (D9-D10=00). When the final divisor is set to 1 the output positive pulse width is equal to the input pulse period. All outputs are complementary and will drive long lines. TTL outputs are back-matched and will drive terminated or unterminated loads. NECL outputs can drive 50 Ω loads terminated into -2 V or AC-coupled 50 Ω loads.

A complementary NECL input is logically ORed with a TTL/Small Signal input, enabling the unit to accept TTL input, small signals (≥40 mV), single-ended or differential NECL input, AC-coupled sinewave or other logic inputs. There is an Input Mode switch and a Threshold Voltage switch. For differential NECL inputs, both SMAs are used with both switches up. For single-ended NECL input the lower SMA is used with Input switch down and the Threshold switch up. For AC-coupled input either SMA can be used with both switches up. For TTL input the BNC input is used with the Input switch down and the Threshold switch up. For small signals the BNC input is used with both switches down.

The NECL inputs are internally terminated to 50 Ω/-2 V in the differential input mode, and the inverted input to 62 Ω/-1.3 V in the single-ended input mode. The BNC input has a ground-referenced 50 Ω termination, and the minimum signal required is only 0.75 V for TTL (switch up) or 40 mV for small signals (switch down):

Desired Input	Connector(s)	Input Mode Switch	Threshold Switch
Differential NECL	Both SMAs	Up	Up
Single-ended NECL	Lower SMA	Down	Up
AC-coupled	Either SMA	Up	Up
TTL	BNC	Down	Up
Small Signals	BNC	Down	Down

The PRL-260BNT is ideal for applications where a frequency divider or prescalar is needed for triggering or down-sampling, and the multiple logic inputs and outputs make it extremely useful in mixed-logic environments. The two phases of output enable applications requiring two different ratios from a common reference frequency. Applications for the PRL-260BNT include data acquisition, test, measurement, R&D, and laser system synchronization.

The unit includes an AC adapter for ready-to-use convenience on the bench or in a system. All I/O connectors are SMA, except for the TTL input, which is BNC. The extruded aluminum housing is suitable for mounting with the optional brackets.

The PRL-260BNT is an improved model of the discontinued PRL-260ANT. It has all the features of the PRL-260ANT plus a small-signal input. The PRL-260BNT is recommended for all new applications.

Typical jitter, as measured on a Tek 11801C Oscilloscope:

Although this is typical performance, this parameter is not tested in Production, nor a guaranteed specification. This scope capture was taken with a previous revision of the product, the PRL-260NT, but the differences between that product and the current revision do not affect jitter.

Symbol	Parameter	Min	Typ	Max	Unit	Comments
R_in	External Clock Input Resistance	49.5	50.0	50.5	Ω	Except f input in single-ended mode
V_TT1	External Clock Input Termination Voltage	-2.2	-2.0	-1.8	V	NECL input
V_TT2	External Clock Input Termination Voltage		0.0		V	TTL/Small Signal input
I_DC+	DC Input Current, +8.5 VDC		+165	+180	mA
I_DC-	DC Input Current, -8.5 VDC		-790	-810	mA
V_DC+	DC Input Voltage, +8.5 VDC	+7.5	+8.5	+12	V
V_DC-	DC Input Voltage, -+8.5 VDC	-12.0	-8.5	-7.5	V
V_AC120	AC/DC Adapter Input Voltage	103	115	127	V	Switched to 120 VAC
V_AC220	AC/DC Adapter Input Voltage	206	230	254	V	Switched to 220 VAC
V_IH1	External Clock Input Hi Level, NECL	-1.13	-0.90	-0.81	V	R_in terminated to V_TT = -2 V
V_IH2	External Clock Input Hi Level, TTL	0.75	0.70	3.00	V	R_in terminated to V_TT = 0 V
V_IH3	External Clock Input Hi Level, Small Signal	0.040	0.035	3.00	V	R_in terminated to V_TT = 0 V
V_IL1	External Clock Input Lo Level, NECL	-1.95	-1.60	-1.48	V	R_in terminated to V_TT = -2 V
V_IL2	External Clock Input Lo Level, TTL	-0.50	0.00	0.50	V	R_in terminated to V_TT = 0 V
V_IL3	External Clock Input Lo Level, Small Signal	-0.50	0.00	0.01	V	R_in terminated to V_TT = 0 V
V_OH1	Output Hi Level @100 MHz, NECL	-1.13	-0.90	-0.81	V	R_L terminated to V_TT = -2 V
V_OH2	Output Hi Level @100 MHz, TTL	2.00	2.20		V	R_L terminated to V_TT = 0 V
V_OL1	Output Lo Level @100 MHz, NECL	-1.95	-1.60	-1.48	V	R_L terminated to V_TT = -2 V
V_OL2	Output Lo Level @100 MHz, TTL	-0.50	0.00	0.50	V	R_L terminated to V_TT = 0 V
t_PLH1	Propagation Delay to f output ↑		2500		ps	From Ext Clk input
t_PLH2	Propagation Delay to NECL f/n output ↑		3750		ps	From Ext Clk input
t_PLH3	Propagation Delay to TTL f/n output ↑		2500		ps	From Ext Clk input
t_r/t_f1	Rise/Fall Times (20%-80%), NECL outputs		600	700	ps	Note (1)
t_r/t_f2	Rise/Fall Times (10%-90%), TTL outputs		1100	1350	ps
t_SKEW1	Skew ↔ Φ1 NECL outputs		50	150	ps
t_SKEW2	Skew ↔ Φ1 TTL outputs		200	400	ps
t_SKEW3	Skew ↔ Φ1 NECL and TTL outputs		1300	1600	ps
t_SKEW4	Skew ↔ Φ1 and Φ2 NECL outputs		50	150	ps	n≠1
f_{MAX In}	Max input clock frequency	1000	1350	1500	MHz
f_{MAX Out1}	Max output frequency	500	675		MHz	NECL outputs
f_{MAX Out2}	Max output frequency	300	350		MHz	TTL outputs
	Size	1.3 x 2.9 x 6.1			in.
	Weight	10			Oz
	Shipping Weight	4			lbs

*All dynamic NECL measurements are made with outputs terminated into 50 Ω/ V_TT, using the PRL-550NQ4X, four channel NECL Terminator, connected to a 50 Ω input sampling oscilloscope. TTL outputs are terminated to 50 Ω.

Notes:

(1). The output rise and fall times of each NECL channel are measured with its complementary output terminated into 50 Ω/ V_TT. An unused complementary 50 Ω output must be either terminated into 50 Ω/ V_TTor AC coupled into a 50 Ω load; otherwise, output waveform distortion and rise time degradation will occur. Use the PRL-ACT-50, Dual Ch. AC-Coupled 50 Ω Termination, for the 50 Ω/V_TTtermination. Use the PRL-SC-104 or PRL-ACX-12dB (0.1 µf DC block and 12 dB AC-coupled attenuator, respectively) for connection of NECL signals to 50 Ω input oscilloscopes.