Low Power, High Speed CCD Buffer Amplifier ADA4800 FEATURES FUNCTIONAL BLOCK DIAGRAM Integrated active load and gain of 1 buffer Very low buffer power consumption As low as 20 mW on chip Power save feature to reduce active load current by GPO control High buffer speed 400 MHz, −3 dB bandwidth 415 V/μs slew rate Fast settling time to 1%, 2 V step: 5 ns Adjustable buffer bandwidth Push-pull output stage Adjustable active load current Small package: 1.6 mm × 1.6 mm × 0.55 mm ADA4800 IN 1 6 ISF 5 VCC 4 IDRV IISF IBUFF IAL ICC VEE 2 +1 OUT 3 09162-001 IIDRV Figure 1. APPLICATIONS CCD image sensor output buffer Digital still cameras Camcorders GENERAL DESCRIPTION The versatility of the ADA4800 allows for seamless interfacing with many CCD sensors from various manufacturers. The ADA4800 is designed to operate at supply voltages as low as 4 V and up to 17 V. It is available in a 1.6 mm × 1.6 mm × 0.55 mm, 6-lead LFCSP package and is rated to operate over the industrial temperature range of −40oC to +85oC. VISF RISF 10kΩ 3V ISF RIDRV 249kΩ 10µF VCC 6 5 IBUFF 15V IDRV IIDRV IISF 4 ADA4800 +1 The buffer of the ADA4800 employs a push-pull output stage architecture, providing drive current and maximum slew capability for both rising and falling signal transitions. At a 5 mA quiescent current setting, it provides 400 MHz, −3 dB bandwidth, which makes this buffer well suited for CCD sensors from machine vision to digital still camera applications. The ADA4800 is ideal for driving the input of the Analog Devices, Inc., 12-bit and 14-bit high resolution analog front ends (AFE) such as the AD9928, AD9990, AD9920A, AD9923A, and AD997x family. + 0.1µF IAL 1 IN 2 3 VEE 49.9Ω OUT 10Ω 1kΩ 22pF 7.5V 7.5V 09162-102 The ADA4800 is voltage buffer integrated with an active load. The buffer is a low power, high speed, low noise, high slew rate, fast settling, fixed gain of 1 monolithic amplifier for chargecoupled device (CCD) applications. For CCD applications, the active load current source (IAL) can load the open source CCD sensor outputs and the buffer can drive the AFE load. The active current load can also be switched off, to use the ADA4800 as just a unity gain buffer. The buffer consumes only 20 mW of static power. In applications where power savings is critical, the ADA4800 features a power save mode (see the Power Save Mode section), which further reduces the total current consumption. The bandwidth of the ADA4800 buffer is also fully adjustable through the IDRV pin. Figure 2. Typical Test Circuit Rev. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2010 Analog Devices, Inc. All rights reserved. ADA4800 TABLE OF CONTENTS Features .............................................................................................. 1 Typical Performance Characteristics ..............................................6 Applications ....................................................................................... 1 Test Circuit .........................................................................................9 Functional Block Diagram .............................................................. 1 Theory of Operation ...................................................................... 10 General Description ......................................................................... 1 Setting Active Load Current with Pin 6 (ISF) ........................ 10 Revision History ............................................................................... 2 Setting Bandwidth with Pin 4 (IDRV)..................................... 10 Specifications..................................................................................... 3 Applications Information .............................................................. 11 Buffer Electrical Characteristics ................................................. 3 Open Source CCD Output Buffer ............................................ 11 Active Current Load Electrical Characteristics ........................ 3 Power Save Mode ....................................................................... 11 Absolute Maximum Ratings............................................................ 4 Power Supply Bypassing ............................................................ 12 Thermal Resistance ...................................................................... 4 Power Sequencing ...................................................................... 12 ESD Caution .................................................................................. 4 Outline Dimensions ....................................................................... 13 Pin Configuration and Function Descriptions ............................. 5 Ordering Guide .......................................................................... 13 REVISION HISTORY 7/10—Rev. 0 to Rev. A Deleted Figure 15 .............................................................................. 7 Changes to Setting Active Load Current with Pin 6 ISF Section and Setting Bandwidth with Pin 4 (IDRV) Section ................... 10 6/10—Revision 0: Initial Version Rev. A | Page 2 of 16 ADA4800 SPECIFICATIONS BUFFER ELECTRICAL CHARACTERISTICS TA = 25°C, VCC = 15 V, VEE = 0 V, RIDRV = 249 kΩ connected to VIDRV, RLOAD = 1 kΩ in parallel with 22 pF in series with 10 Ω, VIN = 7.5 V, unless otherwise noted (see Figure 2 for a test circuit). Table 1. Parameter GAIN Voltage Gain INPUT/OUTPUT CHARACTERISTICS I/O Offset Voltage IDRV Current Input/Output Voltage Range Input Bias Current (IBUFF) DYNAMIC PERFORMANCE −3 dB Bandwidth Slew Rate Rise Time Fall Time 1% Settling Time I/O Delay Time Output Voltage Noise POWER SUPPLY Supply Voltage Range Supply Current (ICC) OPERATING TEMPERATURE RANGE Condition Min Typ Max Unit VIN = 6.5 V to 8.5 V, RISF = 0 Ω 0.995 0.998 1.005 V/V 30 52 41 59 VCC − 1.4 1 mV μA V μA 182 288 400 415 2.2 1.8 5 4.5 4.5 4 0.4 0.35 1.5 MHz MHz MHz V/μs ns ns ns ns ns ns ns ns nV/√Hz RIDRV = 249 kΩ, VIDRV = 15 V VEE + 1.4 RIDRV = 300 kΩ (ICC = 1.1 mA), VOUT = 0.1 V p-p RIDRV = 150 kΩ (ICC = 2.1 mA), VOUT = 0.1 V p-p RIDRV = 50 kΩ (ICC = 4.7 mA), VOUT = 0.1 V p-p VOUT = 2 V step VIN = 7.5 V to 8.5 V, 10% to 90% VIN = 8.5 V to 7.5 V, 10% to 90% VIN = 9.5 V to 7.5 V (falling edge) VIN = 7.5 V to 9.5 V (rising edge) VIN = 8.5 V to 7.5 V (falling edge) VIN = 7.5 V to 8.5 V (rising edge) VIN = 8.5 V to 7.5 V (falling edge) VIN = 7.5 V to 8.5 V (rising edge) @ 20 MHz 4 15 1.4 −40 17 1.8 +85 V mA °C ACTIVE CURRENT LOAD ELECTRICAL CHARACTERISTICS TA = 25°C, VEE = 0 V, VISF = 3 V, RISF = 10 kΩ connected to VISF, VIN = 7.5 V, unless otherwise noted (see Figure 2 for a test circuit). Table 2. Parameter INPUT/OUTPUT CHARACTERISTICS Active Load Current (IAL) ISF Current (IISF) Input Voltage Range OPERATING TEMPERATURE RANGE Condition Min VISF = 0 V VISF = 3 V VISF = 7.5 V RISF = 10 kΩ Typ 1 3 12.7 111 VEE + 1.7 −40 Rev. A | Page 3 of 16 Max Unit 120 VCC +85 μA mA mA μA V °C ADA4800 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. THERMAL RESISTANCE Table 2. θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Parameter Supply Voltage Input Voltage ISF Pin IDRV Pin Storage Temperature Range Operating Temperature Range Junction Temperature Range Rating 18 V VEE to VCC VEE to VCC VEE to VCC −65°C to +150°C −40°C to +85°C −65°C to +150°C Table 3. Thermal Resistance Package Type 6-Lead LFCSP ESD CAUTION Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rev. A | Page 4 of 16 θJA 160 Unit °C/W ADA4800 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS IN 1 VEE 2 OUT 3 EPAD 6 ISF 5 VCC 4 IDRV NOTES 1. EXPOSED PAD IS NOT INTERNALLY CONNECTED TO DIE. CONNECT TO ANY LOW IMPEDANCE NODE OR LEAVE FLOATING. 09162-002 ADA4800 Figure 3. Pin Configuration Table 4. Pin Function Descriptions Pin No. 1 2 3 4 Mnemonic IN VEE OUT IDRV 5 6 VCC ISF EPAD EPAD Description Input. Connect this pin to the CCD sensor output. Negative Power Supply Voltage. Output. Connect this pin to the AFE input. Bandwidth Adjustment Pin. Connect this pin to VCC or an external voltage with an external resistor. This pin allows bandwidth to be controlled by adjusting ICC. This pin can also be used to power down the buffer. Positive Power Supply Voltage. Active Load Current Adjustment Pin. Connect to VCC or an external voltage with an external resistor. This pin can also be connected to the microcontroller logic output through an external resistor for power save mode. This pin can also be used to power down the active current load. Exposed Pad. Not internally connected to die. Connect to any low impedance node or leave floating. Rev. A | Page 5 of 16 ADA4800 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VCC = 7.5 V, VEE = −7.5 V, RIDRV = 249 kΩ connected to VIDRV, VISF = −4.5 V, RISF = 10 kΩ connected to VISF, VIN shunt terminated with 49.9 Ω to 0 V, RLOAD = 1 kΩ in parallel with 22 pF in series with 10 Ω to 0 V. 1 3 RIDRV = 50kΩ 0 0 –1 –3 –6 –2 RIDRV = 150kΩ –9 GAIN (dB) –3 –4 RIDRV = 200kΩ –5 RIDRV = 150kΩ –12 –15 RIDRV = 200kΩ –18 –6 –21 RIDRV = 300kΩ –7 RIDRV = 300kΩ –24 –8 –27 VOUT = 2V p-p –30 1M 10M 100M 1G FREQUENCY (Hz) 09162-003 VOUT = 100mV p-p –9 1M 10M 100M 1G FREQUENCY (Hz) Figure 4. Small Signal Frequency Response with Various IDRV Resistances 09162-006 GAIN (dB) RIDRV = 50kΩ Figure 7. Large Signal Frequency Response with Various IDRV Resistances 3 1.5 2.4 1.0 2.0 0.5 1.6 GAIN (dB) –3 % SETTLING ERROR 0 TA = +25°C TA = +85°C –6 –9 –12 1.2 0 VIN – VOUT VOUT –0.5 0.8 –1.0 0.4 VOUT (V) TA = –40°C VOUT = 100mV p-p FREQUENCY (Hz) –1.5 0 2 3 4 5 6 7 8 9 0 10 TIME (ns) Figure 5. Small Signal Frequency Response at Various Temperatures Figure 8. Settling Time, 2 V to 0 V Output Transition 1.4 2.0 1.4 1.5 1.2 1.5 1.2 1.0 1.0 1.0 1.0 0.5 0.8 0.5 0.8 0 0.6 0.6 VIN – VOUT –0.5 VOUT (V) 0 % SETTLING ERROR 2.0 0.4 –1.0 –0.5 0.4 VIN – VOUT –1.0 0.2 0.2 VOUT –1.5 –2.0 0 1 2 3 4 5 6 7 8 TIME (ns) 9 0 –1.5 –0.2 –2.0 09162-005 % SETTLING ERROR 1 09162-007 1G VOUT (V) 100M VOUT 0 –0.2 0 1 2 3 4 5 6 7 8 TIME (ns) Figure 9. Settling Time, 0 V to 1 V Output Transition Figure 6. Settling Time, 1 V to 0 V Output Transition Rev. A | Page 6 of 16 9 09162-008 10M 09162-004 –15 1M ADA4800 1.2 1.0 PULSE RESPONSE (V) 700 600 1V TO 0V PULSE 0.5V TO 0V PULSE 400 0V TO 0.5V PULSE 300 12 13 14 15 0.6 INPUT 16 SUPPLY VOLTAGE (V) 0.2 –0.2 0 1 3 4 5 6 7 8 9 10 Figure 13. Negative Pulse Response, 1 V to 0 V 1.2 2.5 1.0 2.0 INPUT 0.8 PULSE RESPONSE (V) 0.6 OUTPUT 0.4 0.2 1.5 INPUT 1.0 OUTPUT 0.5 0 1 2 3 4 5 6 7 8 9 10 TIME (ns) –0.5 13 09162-010 –0.2 15 30 ACTIVE LOAD CURRENT, IAL (mA) 2.0 1.5 INPUT 1.0 OUTPUT 0.5 –0.5 6 8 10 12 TIME (ns) 14 09162-011 0 4 21 23 25 27 Figure 14. Negative Pulse Response, 2 V to 0 V 2.5 2 19 TIME (ns) Figure 11. Positive Pulse Response, 0 V to 1 V 0 17 09162-014 0 0 RISF = 10kΩ 25 20 15 10 5 0 –7.5 –5.5 –3.5 –1.5 0.5 2.5 4.5 VISF (V) Figure 15. Input Current vs. Voltage on ISF Pin (VISF) Figure 12. Positive Pulse Response, 0 V to 2 V Rev. A | Page 7 of 16 6.5 09162-018 PULSE RESPONSE (V) 2 TIME (ns) Figure 10. Input to Output Delay Time vs. Supply Voltage PULSE RESPONSE (V) OUTPUT 0.4 0 0V TO 1V PULSE 200 11 0.8 09162-013 500 09162-009 INPUT TO OUTPUT DELAY TIME (ps) 800 ADA4800 0.14 1.6 1.4 IISF 0.10 1.2 0.08 1.0 ICC (mA) CURRENT (mA) 0.12 0.06 IIDRV 0.8 0.6 0.04 0.4 0.02 20 30 40 50 60 70 80 0 –7.5 –5.5 –3.5 –1.5 0.5 2.5 4.5 6.5 09162-021 10 TEMPERATURE (°C) 14 09162-022 0 09162-019 0.2 0 –40 –30 –20 –10 VIDRV (V) Figure 18. ICC vs. Voltage on IDRV Pin (VIDRV) Figure 16. ISF and IDRV Currents vs. Temperature 0 700 600 –5 500 400 –10 300 200 VOS (mV) –20 –25 100 0 –100 –200 –300 –30 –400 –500 –35 –600 –40 –40 –15 10 35 TEMPERATURE (°C) 60 85 –700 09162-020 VOS (mV) –15 0 2 4 6 8 10 12 VIN (V) Figure 17. VOS vs. Temperature Figure 19. Output Offset Voltage vs. Input Voltage Rev. A | Page 8 of 16 ADA4800 TEST CIRCUIT + 1.41mA 0.11mA RISF0.1µF 10kΩ ISF 0.05mA VISF 10µF RIDRV 249kΩ VCC 6 5 IBUFF 15V IDRV IDRV ISF 4 ADA4800 +1 7.5V 3 VEE 49.9Ω 4.68mA 2 IN OUT 10Ω 22pF 7.5V Figure 20. Typical Current Flow Rev. A | Page 9 of 16 1kΩ 09162-026 IAL 1 2.96mA 3V ADA4800 THEORY OF OPERATION The ADA4800 is a buffer integrated with an active load. Each element (the active load and the buffer) operates independently, as described in the following sections. SETTING ACTIVE LOAD CURRENT WITH PIN 6 (ISF) The ISF pin is used to establish the value of the active current load (IAL). Set the ISF current using Equation 1. I ISF = VISF − 1.55 V R ISF + 3 kΩ An external resistor connected between the ISF and the microcontroller GPO pin determines the amount of current that flows into the input pin. This current can be calculated by using Equation 1 and Equation 2. SETTING BANDWIDTH WITH PIN 4 (IDRV) (1) where: VISF is referenced to Pin 2. VISF can be an external voltage source, VCC, or a GPO output as explained in the following paragraphs. RISF is the external resistor between the ISF pin and VISF. The active load current (into the IN pin) is directly proportional to IISF and can be calculated by Equation 2. IAL = IISF × 27 Figure 22 illustrates an ADA4800 application configuration for using this power save feature. (2) The ADA4800 allows for additional power savings by reducing the active load current. The active load current can be logically controlled by connecting the ISF pin to any general-purpose output (GPO) pin of a system microcontroller through an external resistor. A GPO logic high enables the flow of the active load current. Appling –VS or connecting a high-Z to the ISF pin places the ADA4800 into power save mode by shutting down the active load current. The IDRV pin establishes the buffer’s ICC quiescent current. As ICC is increased, power dissipation and bandwidth both increase. Set the current using Equation 3. I IDRV = VIDRV − 0.8 V R IDRV + 28 kΩ (3) where: VIDRV is referenced to Pin 2. VIDRV can be an external voltage source or VCC. RIDRV is the external resistor between the IDRV pin and VIDRV. The ICC current is directly proportional to IIDRV and can be calculated by Equation 4. ICC = IIDRV × 26 Applying –VS to the IDRV pin shuts down the buffer. Rev. A | Page 10 of 16 (4) ADA4800 APPLICATIONS INFORMATION ADA4800 as an open source CCD buffer configured for using this power save feature. Power save mode allows IAL current to be logically controlled by connecting the ISF pin to any generalpurpose output (GPO) pin of the system microcontroller through an external resistor. A GPO logic high enables the flow of input sink current, while a logic low disables the input sink current and asserts the power save mode. OPEN SOURCE CCD OUTPUT BUFFER With low power, high slew rate, and fast settling time, the ADA4800 is the ideal solution for an output buffer for CCD sensors with an open source output configuration. Figure 21 shows a typical application circuit for the ADA4800 as a CCD sensor output buffer. The output of the CCD is connected directly to the IN pin of the ADA4800, whose OUT pin is then ac-coupled into the input of the analog front end. VISF 0V TO 3V GPO PIN RISF 10kΩ VISF 0.1µF RIDRV 249kΩ 47µF 0.1µF VCC 5 IIDRV IISF IBUFF 15V 5 IIDRV IISF IBUFF IDRV IDRV 4 ADA4800 +1 4 ADA4800 +1 IAL 1 IN 2 3 VEE OUT CCD 2 IN AFE 3 VEE Figure 22. Using GPO to Drive ISF Voltage OUT 09162-027 IAL 1 AFE CCD Figure 23 shows an example of the ADA4800 power save feature. Figure 21. Typical Application Block Diagram GPO1 To help reduce the effects of power supply noise coupling into the ISF and IDRV pins, use 0.1 μF ceramic bypass decoupling capacitors. For best performance, place these capacitors as close to each of these pins as is physically possible. POWER SAVE MODE The buffer of the ADA4800 consumes only 20 mW of static power. To achieve even more power savings, the ADA4800 active load current can be switched off during standby mode or reduced during monitoring mode. Figure 22 illustrates the AFE GPO2 MAIN BOARD 20kΩ 20kΩ ISF FPC ADA4800 09162-029 ISF 6 6 0.1µF 15V Figure 23. Example Block Diagram for Sink Current Selection Three combinations of IAL are provided with Figure 23. Selection of the IAL is controlled by the logic signals applied to the GPO1 and GPO2 pins. Table 5 summarizes the IAL selections. Table 5. Input Sink Current Selection Mode Standby Sleep Active GPO1 High-Z 0 High-Z 1 1 GPO2 High-Z 0 1 High-Z 1 Resistance (kΩ) High-Z N/A 20 20 10 Rev. A | Page 11 of 16 Active Load Current, IAL (mA) 0 1.90 3.36 09162-028 + RIDRV 249kΩ 47µF 0.1µF VCC ISF RISF 120kΩ 15V 0.1µF + 0.1µF ADA4800 POWER SUPPLY BYPASSING POWER SEQUENCING Attention must be paid to bypassing the power supply pin of the ADA4800. Use high quality capacitors with low equivalent series resistance (ESR), such as multilayer ceramic capacitors (MLCCs), to minimize supply voltage ripple and power dissipation. A large, usually tantalum, 2.2 μF to 47 μF capacitor located in close proximity to the ADA4800 is required to provide good decoupling for lower frequency signals. The actual value is determined by the circuit transient and frequency requirements. In addition, 0.1 μF MLCC decoupling capacitors should be located as close to the power supply pin as is physically possible, no more than ⅛ inch away. The ground returns should terminate immediately into the ground plane. Locating the bypass capacitor return close to the load return minimizes ground loops and improves performance. All I/O pins are ESD protected with internal back-to-back diodes connected to VCC and GND as shown in Figure 24. With the ADA4800 supply turned off (VCC = 0 V), a voltage on an I/O pin can turn on the protection diodes and cause permanent damage or destroy the IC. To prevent this condition during power-on, no voltages should be applied to any I/O pins until VCC is fully on and settled. During power-off, I/O pin voltages should be removed or reduced to 0 V before VCC is turned off. VCC ADA4800 09162-030 EXTERNAL PIN Figure 24. Simplified Input/Output Circuitry In the presence of a voltage on an I/O pin with VCC = 0 V, the current should be limited to 5 mA or less by the source or by adding a series resistor. Rev. A | Page 12 of 16 ADA4800 OUTLINE DIMENSIONS 1.15 1.05 0.95 1.65 1.60 SQ 1.55 0.50 BSC 6 4 0.60 0.50 0.40 EXPOSED PAD 0.375 0.300 0.225 3 TOP VIEW 0.60 0.55 0.50 0.05 MAX 0.02 NOM SEATING PLANE 0.30 0.25 0.20 1 BOTTOM VIEW PIN 1 INDICATOR (R 0.15) FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. 0.152 REF 101409-A PIN 1 INDEX AREA Figure 25. 6-Lead Lead Frame Chip Scale Package [LFCSP_UD] 1.60 mm × 1.60 mm Body, Ultra Thin, Dual Lead (CP-6-4) Dimensions shown in millimeters ORDERING GUIDE Model 1 ADA4800ACPZ-R2 ADA4800ACPZ-R7 ADA4800ACPZ-RL 1 Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C Package Description 6-Lead Lead Frame Chip Scale Package [LFCSP_UD] 6-Lead Lead Frame Chip Scale Package [LFCSP_UD] 6-Lead Lead Frame Chip Scale Package [LFCSP_UD] Z = RoHS Compliant Part. Rev. A | Page 13 of 16 Package Option CP-6-4 CP-6-4 CP-6-4 Branding H2E H2E H2E ADA4800 NOTES Rev. A | Page 14 of 16 ADA4800 NOTES Rev. A | Page 15 of 16 ADA4800 NOTES ©2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09162-0-7/10(A) Rev. A | Page 16 of 16