Intersil Corporation HA7210 Datasheet

HA7210

Data Sheet February 1999 File Number 3389.8

10kHz to 10MHz, Low Power Crystal Oscillator

The HA7210 is a very low power crystal-controlled oscillators that can be externally programmed to operate between 10kHz and 10MHz. For normal operation it requires only the addition of a crystal. The part exhibits very high stability over a wide operating voltage and temperature range.

The HA7210 also features a disable mode that switches the output to a high impedance state. This feature is useful for minimizing power dissipation during standby and when multiple oscillator circuits are employed.

Ordering Information

PART NUMBER

(BRAND)

HA7210IP -40 to 85 8 Ld PDIP E8.3 HA7210IB

(H7210I) HA7210Y -40 to 85 DIE

TEMP.

RANGE (oC) PACKAGE

-40 to 85 8 Ld SOIC M8.15

PKG.

NO.

Pinout

HA7210

(PDIP, SOIC)

TOP VIEW

OSC IN

OSC OUT

ENABLE

FREQ 2

FREQ 1

OUTPUT

Features

• Single Supply Operation at 32kHz . . . . . . . . . . . .2V to 7V

• Operating Frequency Range . . . . . . . . . 10kHz to 10MHz

• Supply Current at 32kHz . . . . . . . . . . . . . . . . . . . . . . 5µA

• Supply Current at 1MHz. . . . . . . . . . . . . . . . . . . . . 130µA

• Drives 2 CMOS Loads

• Only Requires an External Crystal for Operation

Applications

• Battery Powered Circuits

• Remote Metering

• Embedded Microprocessors

• Palm Top/Notebook PC

• Related Literature

- AN9334, Improving HA7210 Start-Up Time

Typical Application Circuit

0.1µF

32.768kHz CRYSTAL

1 2

HA7210

3 4

(NOTE 1)

7 6

32.768kHz

CLOCK

32.768kHz MICROPOWER CLOCK OSCILLATOR

NOTE:

1. Internal pull-up resistors provided on EN, FREQ1, and FREQ2 inputs.

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

http://www.intersil.com or 407-727-9207

Simpliﬁed Block Diagram

(NOTE 2)

ENABLE

HA7210

EXTERNAL CRYSTAL

FREQ 1

FREQ 2

VDD - 1.4V

VDD - 2.2V

VDD - 3.0V

VDD - 3.8V

BIAS

(NOTE 2)

1 OF 4

DECODE

OSC IN 2 3 OSC OUT

15pF

BUFFER AMP

15pF

OSCILLATOR

OUT

LEVEL

SHIFTER

OUTPUT

BUFFER

FREQUENCY SELECTION TRUTH TABLE

ENABLE FREQ 1 FREQ 2 SWITCH OUTPUT RANGE

111S 110S 101S 100S 0 X X X High Impedance

NOTE:

2. Logic input pull-up resistors are constant current source of 0.4µA.

, S1B, S

1C 2 3 4

10kHz - 100kHz 100kHz - 1MHz 1MHz - 5MHz 5MHz - 10MHz+

HA7210

Absolute Maximum Ratings Thermal Information

Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10V

Voltage (Any Pin). . . . . . . . . . . . . . . . . . . . VSS-0.3V to VDD+0.3V

ESD Rating

Human Body Model (Per MIL-STD-883 Method 3015.7). . .4000V

Operating Conditions

Temperature Range (Note 3) . . . . . . . . . . . . . . . . . . . -40oC to 85oC

CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operationofthe device at these or any other conditions above those indicated in the operational sections of this speciﬁcation is not implied.

NOTES:

3. This product is production tested at 25oC only.

4. θJA is measured with the component mounted on an evaluation PC board in free air.

Thermal Resistance (Typical, Note 4) θJA (oC/W)

PDIP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

Maximum Junction Temperature (Plastic Package) . . . . . . . .150oC

Maximum Storage Temperature Range. . . . . . . . . . -65oC to 150oC

Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300oC

(SOIC - Lead Tips Only)

Electrical Speciﬁcations V

= GND, TA = 25oC, Unless Otherwise Speciﬁed

VDD= 5V VDD = 3V

PARAMETER TEST CONDITIONS

VDD Supply Range f IDD Supply Current f

= 32kHz 2 5 7 - - - V

OSC

= 32kHz, EN = 0 (Standby) - 5.0 9.0 - - - µA

OSC

= 32kHz, CL = 10pF (Note 5),

OSC

- 5.2 10.2 - 3.6 6.1 µA

UNITSMIN TYP MAX MIN TYP MAX

EN = 1, Freq1 = 1, Freq2 = 1 f

= 32kHz, CL = 40pF, EN = 1,

OSC

- 10 15 - 6.5 9 µA

Freq1 = 1, Freq2 = 1 f

= 1MHz, CL = 10pF (Note 5),

OSC

- 130 200 - 90 180 µA

EN = 1, Freq1 = 0, Freq2 = 1 f

= 1MHz, CL = 40pF, EN = 1,

OSC

- 270 350 - 180 270 µA

Freq1 = 0, Freq2 = 1 VOH Output High Voltage I VOL Output Low Voltage I IOH Output High Current V IOL Output Low Current V Three-State Leakage Current V

IIN Enable, Freq1, Freq2 Input Current VIN = VSS to V

= -1mA 4.0 4.9 - - 2.8 - V

OUT

= 1mA - 0.07 0.4 - 0.1 - V

OUT

≥ 4V - -10 -5 - - - mA

OUT

≤ 0.4V 5.0 10.0 - - - - mA

OUT

= 0V, 5V, TA = 25oC, -40oC - 0.1 - - - - nA

OUT

= 0V, 5V, TA = 85oC - 10 - - - - nA

OUT

- 0.4 1.0 - - - µA VIHInput High Voltage Enable, Freq1, Freq2 2.0 - - - - - V VIL Input Low Voltage Enable, Freq1, Freq2 - - 0.8 - - - V Enable Time CL = 18pF, RL = 1kΩ - 800 - - - - ns Disable Time CL = 18pF, RL = 1kΩ -90- - - - ns tr Output Rise Time 10% - 90%,f tf Output Fall Time 10% - 90%, f Duty Cycle, Packaged Part Only (Note 6) CL = 40pF, f Duty Cycle, (See Typical Curves) CL = 40pF, f Frequency Stability vs Supply Voltage f Frequency Stability vs Temperature f Frequency Stability vs Load f

= 32kHz, VDD = 5V, CL= 10pF - 1 - - - - ppm/V

OSC

= 32kHz, VDD = 5V, CL = 10pF - 0.1 - - - - ppm/oC

OSC

= 32kHz, VDD = 5V, CL = 10pF - 0.01 - - - - ppm/pF

OSC

= 32kHz, CL= 40pF - 12 25 - 12 - ns

OSC

= 32kHz, CL = 40pF - 12 25 - 14 - ns

OSC

= 1MHz 40 54 60 - - - %

OSC

= 32kHz - 41 - - 44 - %

OSC

NOTES:

5. Calculated using the equation IDD = IDD (No Load) + (VDD) (f

OSC

)(CL)

6. Duty cycle will vary with supply voltage, oscillation frequency, and parasitic capacitance on the crystal pins.

HA7210

Test Circuit

1000pF

+5V

1 2

HA7210

3 4

FIGURE 1.

ENABLE

FREQ 2

FREQ 1

6 5

18pF

P-P

OUT

input

0.1µF

P-P

50Ω

In production the HA7210 is tested with a 32kHz and a 1MHz crystal. However for characterization purposes data was taken using a sinewave generator as the frequency determining element, as shown in Figure 1. The 1V is a smaller amplitude than what a typical crystal would generate so the transitions are slower. In general the Generator data will show a “worst case” number for I duty cycle, and rise/fall time. The Generator test method is useful for testing a variety of frequencies quickly and provides curves which can be used for understanding performance trends. Data for the HA7210 using crystals has also been taken. This data has been overlaid onto the generator data to provide a reference for comparison.

Application Information

Theory Of Operation

The HA7210 is a Pierce Oscillator optimized for low pow er consumption, requiring no external components except for a bypass capacitor and a Parallel Mode Crystal. The Simplified Block Diagram shows the Crystal attached to pins 2 and 3, the Oscillator input and output. The crystal drive circuitry is detailed showing the simple CMOS inverter stage and the P-channel device being used as biasing resistor R operate mostly in its linear region increasing the amplitude of the oscillation until limited by its transconductance and voltage rails, V

and VRN. The inverter is self biasing using RF to

center the oscillating wavef orm at the input threshold. Do not interfere with this bias function with external loads or excessive leakage on pin 2. Nominal value for R frequency range to 7MΩ in the highest frequency range.

The HA7210 optimizes its power for 4 frequency ranges selected by digital inputs Freq1 and Freq2 as shown in the Block Diagram. Internal pull up resistors (constant current

0.4µA) on Enable, Freq1 and Freq2 allow the user simply to leave one or all digital inputs not connected for a corresponding “1” state. All digital inputs may be left open for 10kHz to 100kHz operation.

A current source develops 4 selectable reference voltages through series resistors. The selected voltage, V buffered and used as the negative supply rail for the oscillator section of the circuit. The use of a current source in the reference string allows for wide supply variation with minimal effect on performance. The reduced operating

. The inverter will

is 17MΩ in the lowest

, is

voltage of the oscillator section reduces power consumption and limits transconductance and bandwidth to the frequency range selected. For frequencies at the edge of a range, the higher range may provide better performance.

The OSC OUTwaveformon pin 3 is squaredup through a series of inverters to the output drive stage. The Enable function is implemented with a NAND gate in the inverter string, gating the signal to the level shifter and output stage. Also during Disable the output is set to a high impedance state useful for minimizing powerduring standby and when multiple oscillators are OR’ed to a single node.

Design Considerations

The low power CMOS transistors are designed to consume power mostly during transitions. Keeping these transitions short requires a good decoupling capacitor as close as possible to the supply pins 1 and 4. A ceramic 0.1µF is recommended. Additional supply decoupling on the circuit board with 1µFto10µF will further reduce overshoot,ringing and power consumption. The HA7210, when compared to a crystal and inverter alone, will speed clock transition times, reducing power consumption of all CMOS circuitry run from that clock.

Pow erconsumption may be further reduced by minimizing the capacitance on moving nodes. The majority of the power will be used in the output stage driving the load. Minimizing the load and parasitic capacitance on the output, pin 5, will play the major role in minimizing supply current. A secondary source of wasted supply current is parasitic or crystal load capacitance on pins 2 and 3. The HA7210 is designed to work with most available crystals in its frequency range with no external components required. Two 15pF capacitors are internally switched onto crystal pins 2 and 3 on the HA7210 to compensate the oscillator in the 10kHz to 100kHz frequency range.

The supply current of the HA7210 may be approximately calculated from the equation:

= IDD(Disabled) + VDD × f

= Total supply current

= Total voltage from VDD (pin 1) to VSS (pin 4)

= Frequency of Oscillation

OSC

= Output (pin 5) load capacitance

EXAMPLE #1:

= 5V, f

(Disabled) = 4.5µA (Figure 10)

= 4.5µA + (5V)(100kHz)(30pF) = 19.5µA

Measured I

= 100kHz, CL = 30pF

OSC

= 20.3µA

EXAMPLE #2:

= 5V, f

(Disabled) = 75µA (Figure 9)

= 75µA + (5V)(5MHz)(30pF) = 825µA

Measured I

= 5MHz, CL = 30pF

OSC

= 809µA

× CLwhere:

OSC

HA7210

Crystal Selection

For general purpose applications, a Parallel Mode Crystal is a good choice for use with the HA7210. However for applications where a precision frequency is required, the designer needs to consider other factors.

Crystals are available in two types or modes of oscillation, Series and Parallel. Series Mode crystals are manufactured to operate at a speciﬁed frequency with zero load capacitance and appear as a near resistive impedance when oscillating. Parallel Mode crystals are manufactured to operate with a speciﬁc capacitive load in series, causing the crystal to operate at a more inductive impedance to cancel the load capacitor. Loading a crystal with a different capacitance will “pull” the frequency off its value.

The HA7210 has 4 operating frequency ranges. The higher three ranges do not add any loading capacitance to the oscillator circuit. The lowest range, 10kHz to 100kHz, automatically switches in two 15pF capacitors onto OSC IN and OSC OUT to eliminate potential start-up problems. These capacitors create an effective crystal loading capacitor equal to the series combination of these two capacitors. For the HA7210 in the lowest range, the effective loading capacitance is 7.5pF. Therefore the choice for a crystal, in this range, should be a Parallel Mode crystal that requires a 7.5pF load.

In the higher 3 frequency ranges, the capacitance on OSC IN and OSC OUT will be determined by package and layout parasitics, typically 4 to 5pF. Ideally the choice for crystal should be a Parallel Mode set for 2.5pF load. A crystal manufactured for a different load will be “pulled” from its nominal frequency (see Crystal Pullability).

XTAL C

2 OSC IN

3 OSC OUT

HA7210

FIGURE 2.

+5V

1 V

REG

frequency. In Method two these two goals can be at odds with each other; either the oscillator is trimmed to frequency by de-tuning the load circuit, or stability is increased at the expense of absolute frequency accuracy.

Method one allows these two conditions to be met independently. The two ﬁxed capacitors, C the optimum load to the oscillator and crystal. C

and C2, provide

adjusts the

frequency at which the circuit oscillates without appreciably changing the load (and thus the stability) of the system. Once a value for C

has been determined for the particular

type of crystal being used, it could be replaced with a ﬁxed capacitor. For the most precise control over oscillator frequency, C

should remain adjustable.

This three capacitor tuning method will be more accurate and stable than method two and is recommended for 32kHz tuning fork crystals; without it they may leap into an overtone mode when power is initially applied.

Method two has been used for many years and may be preferred in applications where cost or space is critical. Note that in both cases the crystal loading capacitors are connected between the oscillator and V

; do not use V

as an AC ground. The Simpliﬁed Block Diagram shows that the oscillating inverter does not directly connect to V referenced to V

and VRN. Therefore VDD is the best AC

but is

ground available.

+5V

2 OSC IN

XTAL

3 OSC OUT

HA7210

FIGURE 3.

1 V

REG

Typical values of the capacitors in Figure 2 are shown below. Some trial and error may be required before the best combination is determined. The values listed are total capacitance including parasitic or other sources. Remember that in the 10kHz to 100kHz frequency range setting the HA7210 switches in two internal 15pF capacitors.

Frequency Fine Tuning

Two Methods will be discussed for ﬁne adjustment of the crystal frequency. The ﬁrst and preferred method (Figure 2), provides better frequency accuracy and oscillator stability than method two (Figure 3). Method one also eliminates start-up problems sometimes encountered with 32kHz tuning fork crystals.

For best oscillator performance, two conditions must be met: the capacitive load must be matched to both the inverter and crystal to provide ideal conditions for oscillation, and the frequency of the oscillator must be adjustable to the desired

CRYSTAL

FREQUENCY

32kHz 33pF 5pF to 50pF

1MHz 33pF 5pF to 50pF 2MHz 25pF 5pF to 50pF 4MHz 22pF 5pF to 100pF

LOAD CAPS

C1, C

TRIMMER CAP

+ 10 hidden pages