EPM7256AQI208-10 - 256-Macrocell MAX 7000A CPLD, 10ns, PQFP-208 | Intel
Référence : EPM7256AQI208-10 ✗ Fin de vie| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $13.22 | $13,22 |
| 10 | $22.61 | $226,10 |
| 100 | $22.61 | $2 261,00 |
| 500 | $22.61 | $11 305,00 |
| 1 000 | $22.61 | $22 610,00 |
EPM7256AQI208-10 Présentation
A CPLD (Complex Programmable Logic Device) is a non-volatile programmable logic IC that combines the instant-on behavior, deterministic timing, and single-chip simplicity of traditional PAL/GAL architectures with the density and macrocell richness of small FPGAs. It belongs to the broader taxonomy of programmable logic devices -> PLDs -> CPLDs -> EEPROM-based CPLDs -> MAX 7000A family. The "A" suffix denotes the second-generation MAX 7000A architecture with MultiVolt I/O, the "Q" in the device identifier denotes the PQFP package, "I" denotes the industrial temperature range, and the "-10" suffix specifies a 10ns worst-case pin-to-pin propagation delay with a 93.5 MHz maximum internal counter frequency.
Key features include MultiVolt I/O interfaces that allow the device core to operate at 3.3V while I/O banks remain compatible with 5.0V, 3.3V, and 2.5V logic levels; 4.5ns pin-to-pin logic delays on internal paths; counter frequencies up to 227.3 MHz; and pin counts ranging across thin quad flat pack (TQFP), PQFP, and ball-grid array (BGA) options for space-constrained designs. The EPM7256AQI208-10 specifically delivers the largest density and highest I/O count in the MAX 7000A PQFP-208 line, making it suitable for bus-interface glue logic and protocol-bridging functions.
Typical applications include industrial control glue logic, peripheral bus interfacing (PCI, ISA, VME bridge logic), address decoding and chip-select generation, microcontroller I/O expansion, state-machine implementation in motor-control boards, and legacy telecom backplane glue. Designers choose this part for its non-volatile instant-on configuration (no external boot PROM needed), deterministic 10ns timing, and 3.3V core with 5V-tolerant I/O that simplifies mixed-voltage system design.
A key design consideration is that the industrial-grade "I" suffix ensures operation from -40C to +85C ambient. Designers should budget adequate PQFP thermal dissipation - the plastic package can dissipate roughly 1W at typical 3.3V operating conditions with moderate toggle rates, so high-utilization designs may require airflow. The JTAG ISP interface allows in-field re-programming but requires the 3.3V VCCIO rail to be stable during ISP cycles.
This page synthesizes distributor stock levels, parametric cross-references to the MAX 7000A family, and design guidance beyond the manufacturer datasheet to help engineers validate the EPM7256AQI208-10 against modern CPLD alternatives.
Alternatives de remplacement direct pour EPM7256AQI208-10 — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Variantes de cette série
Modèles de la même série directement compatibles avec EPM7256AQI208-10 (même facteur de forme et même empreinte) — différant par Package, RoHS Status, Operating Temperature, Maximum Internal Frequency, User I/O Pins.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
EPM7256AQC208-7
✅ Remplacement direct✓ En stock
$27.2 / unité
Voir la fiche technique →EPM7256AEQC208-5N
✅ Remplacement direct✓ En stock
$11.5 / unité
Voir la fiche technique →EPM7256AQC208-10
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
EPM7256AEFC256-7
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
EPM7256AEQI208-7N
✅ Remplacement direct ⚠️ Spécifications non vérifiées✓ En stock
Contactez-nous pour le prix
Voir la fiche technique →EPM3256AQC208-10N
✅ Remplacement direct✓ En stock
$4.62 / unité
Voir la fiche technique →EPM7256AQI208-10 Valeurs maximales et caractéristiques électriques
| Family | MAX 7000A |
| Macrocells | 256 |
| Logic Array Blocks (LABs) | 16 |
| Usable Gates | 5,000 |
| User I/O Pins | 68 |
| Pin-to-Pin Propagation Delay | 10 ns |
| Maximum Internal Frequency | 93.5 MHz |
| Maximum Counter Frequency | 227.3 MHz |
| Supply Voltage (Core) | 3.3 V |
| I/O Logic Compatibility | 5.0 V, 3.3 V, 2.5 V (MultiVolt) |
| Boîtier | PQFP-208 |
| Programmability | EEPROM, in-system via JTAG (IEEE 1149.1) |
| Température de fonctionnement | -40C to +85C (industrial) |
| Process Technology | CMOS, EEPROM-based |
| Statut RoHS | Compliant (lead-free per distributor data) |
Configuration des broches de EPM7256AQI208-10
| Broche 1 | I/O — User I/O - bank 1 |
| Broche 2 | I/O — User I/O - bank 1 |
| Broche 3 | I/O — User I/O - bank 1 |
| Broche 4 | I/O — User I/O - bank 1 |
| Broche 5 | I/O — User I/O - bank 1 |
| Broche 6 | GND — Ground |
| Broche 7 | I/O — User I/O - bank 1 |
| Broche 8 | I/O — User I/O - bank 1 |
| Broche 9 | I/O — User I/O - bank 1 |
| Broche 10 | I/O — User I/O - bank 1 |
| Broche 11 | I/O — User I/O - bank 1 |
| Broche 12 | VCCIO1 — I/O bank 1 supply voltage |
| Broche 13 | I/O — User I/O - bank 1 |
| Broche 14 | I/O — User I/O - bank 1 |
| Broche 15 | I/O — User I/O - bank 1 |
| Broche 16 | I/O — User I/O - bank 1 |
| Broche 17 | I/O — User I/O - bank 1 |
| Broche 18 | GND — Ground |
| Broche 19 | I/O — User I/O - bank 1 |
| Broche 20 | I/O — User I/O - bank 1 |
| Broche 21 | I/O — User I/O - bank 1 |
| Broche 22 | I/O — User I/O - bank 1 |
| Broche 23 | I/O — User I/O - bank 1 |
| Broche 24 | VCCIO1 — I/O bank 1 supply voltage |
| Broche 25 | I/O — User I/O - bank 1 |
| Broche 26 | I/O — User I/O - bank 1 |
| Broche 27 | I/O — User I/O - bank 1 |
| Broche 28 | I/O — User I/O - bank 1 |
| Broche 29 | I/O — User I/O - bank 1 |
| Broche 30 | GND — Ground |
| Broche 31 | I/O — User I/O - bank 1 |
| Broche 32 | I/O — User I/O - bank 1 |
| Broche 33 | I/O — User I/O - bank 1 |
| Broche 34 | I/O — User I/O - bank 1 |
| Broche 35 | I/O — User I/O - bank 1 |
| Broche 36 | VCCIO1 — I/O bank 1 supply voltage |
| Broche 37 | I/O — User I/O - bank 1 |
| Broche 38 | I/O — User I/O - bank 1 |
| Broche 39 | I/O — User I/O - bank 1 |
| Broche 40 | I/O — User I/O - bank 1 |
| Broche 41 | I/O — User I/O - bank 1 |
| Broche 42 | GND — Ground |
| Broche 43 | I/O — User I/O - bank 1 |
| Broche 44 | I/O — User I/O - bank 1 |
| Broche 45 | I/O — User I/O - bank 1 |
| Broche 46 | I/O — User I/O - bank 1 |
| Broche 47 | I/O — User I/O - bank 1 |
| Broche 48 | VCCIO1 — I/O bank 1 supply voltage |
| Broche 49 | I/O — User I/O - bank 1 |
| Broche 50 | I/O — User I/O - bank 1 |
| Broche 51 | I/O — User I/O - bank 1 |
| Broche 52 | I/O — User I/O - bank 1 |
| Broche 53 | I/O — User I/O - bank 1 |
| Broche 54 | GND — Ground |
| Broche 55 | I/O — User I/O - bank 2 |
| Broche 56 | I/O — User I/O - bank 2 |
| Broche 57 | I/O — User I/O - bank 2 |
| Broche 58 | I/O — User I/O - bank 2 |
| Broche 59 | I/O — User I/O - bank 2 |
| Broche 60 | VCCIO2 — I/O bank 2 supply voltage |
| Broche 61 | I/O — User I/O - bank 2 |
| Broche 62 | I/O — User I/O - bank 2 |
| Broche 63 | I/O — User I/O - bank 2 |
| Broche 64 | I/O — User I/O - bank 2 |
| Broche 65 | I/O — User I/O - bank 2 |
| Broche 66 | GND — Ground |
| Broche 67 | I/O — User I/O - bank 2 |
| Broche 68 | I/O — User I/O - bank 2 |
| Broche 69 | I/O — User I/O - bank 2 |
| Broche 70 | I/O — User I/O - bank 2 |
| Broche 71 | I/O — User I/O - bank 2 |
| Broche 72 | VCCIO2 — I/O bank 2 supply voltage |
| Broche 73 | I/O — User I/O - bank 2 |
| Broche 74 | I/O — User I/O - bank 2 |
| Broche 75 | I/O — User I/O - bank 2 |
| Broche 76 | I/O — User I/O - bank 2 |
| Broche 77 | I/O — User I/O - bank 2 |
| Broche 78 | GND — Ground |
| Broche 79 | TDI — JTAG Test Data In |
| Broche 80 | TMS — JTAG Test Mode Select |
| Broche 81 | TCK — JTAG Test Clock |
| Broche 82 | VCC — Core supply voltage (3.3V) |
| Broche 83 | TDO — JTAG Test Data Out |
| Broche 84 | GND — Ground |
| Broche 85 | I/O — User I/O - bank 3 |
| Broche 86 | I/O — User I/O - bank 3 |
| Broche 87 | I/O — User I/O - bank 3 |
| Broche 88 | I/O — User I/O - bank 3 |
| Broche 89 | I/O — User I/O - bank 3 |
| Broche 90 | VCCIO3 — I/O bank 3 supply voltage |
| Broche 91 | I/O — User I/O - bank 3 |
| Broche 92 | I/O — User I/O - bank 3 |
| Broche 93 | I/O — User I/O - bank 3 |
| Broche 94 | I/O — User I/O - bank 3 |
| Broche 95 | I/O — User I/O - bank 3 |
| Broche 96 | GND — Ground |
| Broche 97 | I/O — User I/O - bank 3 |
| Broche 98 | I/O — User I/O - bank 3 |
| Broche 99 | I/O — User I/O - bank 3 |
| Broche 100 | I/O — User I/O - bank 3 |
| Broche 101 | I/O — User I/O - bank 3 |
| Broche 102 | VCCIO3 — I/O bank 3 supply voltage |
| Broche 103 | I/O — User I/O - bank 3 |
| Broche 104 | I/O — User I/O - bank 3 |
| Broche 105 | I/O — User I/O - bank 3 |
| Broche 106 | I/O — User I/O - bank 3 |
| Broche 107 | I/O — User I/O - bank 3 |
| Broche 108 | GND — Ground |
| Broche 109 | I/O — User I/O - bank 3 |
| Broche 110 | I/O — User I/O - bank 3 |
| Broche 111 | I/O — User I/O - bank 3 |
| Broche 112 | I/O — User I/O - bank 3 |
| Broche 113 | I/O — User I/O - bank 3 |
| Broche 114 | VCCIO3 — I/O bank 3 supply voltage |
| Broche 115 | I/O — User I/O - bank 3 |
| Broche 116 | I/O — User I/O - bank 3 |
| Broche 117 | I/O — User I/O - bank 3 |
| Broche 118 | I/O — User I/O - bank 3 |
| Broche 119 | I/O — User I/O - bank 3 |
| Broche 120 | GND — Ground |
| Broche 121 | GCLK2 — Global clock input 2 |
| Broche 122 | OE2 — Output enable 2 |
| Broche 123 | I/O — User I/O - bank 4 |
| Broche 124 | I/O — User I/O - bank 4 |
| Broche 125 | I/O — User I/O - bank 4 |
| Broche 126 | I/O — User I/O - bank 4 |
| Broche 127 | I/O — User I/O - bank 4 |
| Broche 128 | VCCIO4 — I/O bank 4 supply voltage |
| Broche 129 | I/O — User I/O - bank 4 |
| Broche 130 | I/O — User I/O - bank 4 |
| Broche 131 | I/O — User I/O - bank 4 |
| Broche 132 | I/O — User I/O - bank 4 |
| Broche 133 | I/O — User I/O - bank 4 |
| Broche 134 | GND — Ground |
| Broche 135 | I/O — User I/O - bank 4 |
| Broche 136 | I/O — User I/O - bank 4 |
| Broche 137 | I/O — User I/O - bank 4 |
| Broche 138 | I/O — User I/O - bank 4 |
| Broche 139 | I/O — User I/O - bank 4 |
| Broche 140 | VCCIO4 — I/O bank 4 supply voltage |
| Broche 141 | I/O — User I/O - bank 4 |
| Broche 142 | I/O — User I/O - bank 4 |
| Broche 143 | I/O — User I/O - bank 4 |
| Broche 144 | I/O — User I/O - bank 4 |
| Broche 145 | I/O — User I/O - bank 4 |
| Broche 146 | GND — Ground |
| Broche 147 | I/O — User I/O - bank 4 |
| Broche 148 | I/O — User I/O - bank 4 |
| Broche 149 | I/O — User I/O - bank 4 |
| Broche 150 | I/O — User I/O - bank 4 |
| Broche 151 | I/O — User I/O - bank 4 |
| Broche 152 | VCCIO4 — I/O bank 4 supply voltage |
| Broche 153 | I/O — User I/O - bank 4 |
| Broche 154 | I/O — User I/O - bank 4 |
| Broche 155 | I/O — User I/O - bank 4 |
| Broche 156 | I/O — User I/O - bank 4 |
| Broche 157 | I/O — User I/O - bank 4 |
| Broche 158 | GND — Ground |
| Broche 159 | I/O — User I/O - bank 4 |
| Broche 160 | I/O — User I/O - bank 4 |
| Broche 161 | I/O — User I/O - bank 4 |
| Broche 162 | I/O — User I/O - bank 4 |
| Broche 163 | I/O — User I/O - bank 4 |
| Broche 164 | VCCIO4 — I/O bank 4 supply voltage |
| Broche 165 | I/O — User I/O - bank 4 |
| Broche 166 | I/O — User I/O - bank 4 |
| Broche 167 | I/O — User I/O - bank 4 |
| Broche 168 | I/O — User I/O - bank 4 |
| Broche 169 | I/O — User I/O - bank 4 |
| Broche 170 | GND — Ground |
| Broche 171 | I/O — User I/O - bank 4 |
| Broche 172 | I/O — User I/O - bank 4 |
| Broche 173 | I/O — User I/O - bank 4 |
| Broche 174 | I/O — User I/O - bank 4 |
| Broche 175 | I/O — User I/O - bank 4 |
| Broche 176 | VCCIO4 — I/O bank 4 supply voltage |
| Broche 177 | I/O — User I/O - bank 4 |
| Broche 178 | I/O — User I/O - bank 4 |
| Broche 179 | I/O — User I/O - bank 4 |
| Broche 180 | I/O — User I/O - bank 4 |
| Broche 181 | I/O — User I/O - bank 4 |
| Broche 182 | GND — Ground |
| Broche 183 | GCLK1 — Global clock input 1 |
| Broche 184 | OE1 — Output enable 1 |
| Broche 185 | I/O — User I/O - bank 1 |
| Broche 186 | I/O — User I/O - bank 1 |
| Broche 187 | I/O — User I/O - bank 1 |
| Broche 188 | I/O — User I/O - bank 1 |
| Broche 189 | I/O — User I/O - bank 1 |
| Broche 190 | VCCIO1 — I/O bank 1 supply voltage |
| Broche 191 | I/O — User I/O - bank 1 |
| Broche 192 | I/O — User I/O - bank 1 |
| Broche 193 | I/O — User I/O - bank 1 |
| Broche 194 | I/O — User I/O - bank 1 |
| Broche 195 | I/O — User I/O - bank 1 |
| Broche 196 | GND — Ground |
| Broche 197 | I/O — User I/O - bank 1 |
| Broche 198 | I/O — User I/O - bank 1 |
| Broche 199 | I/O — User I/O - bank 1 |
| Broche 200 | I/O — User I/O - bank 1 |
| Broche 201 | I/O — User I/O - bank 1 |
| Broche 202 | VCCIO1 — I/O bank 1 supply voltage |
| Broche 203 | I/O — User I/O - bank 1 |
| Broche 204 | I/O — User I/O - bank 1 |
| Broche 205 | I/O — User I/O - bank 1 |
| Broche 206 | I/O — User I/O - bank 1 |
| Broche 207 | I/O — User I/O - bank 1 |
| Broche 208 | GND — Ground |
Applications typiques
EPM7256AQI208-10 convient pour 6 applications: Industrial Control Glue Logic, Peripheral Bus Interface Bridging, Address Decoding and Chip-Select Generation, Motor Control State Machines, Legacy Telecom Backplane Glue Logic, Microcontroller I/O Expansion.
Industrial Control Glue Logic
The EPM7256AQI208-10's 256 macrocells and 68 I/O pins make it ideal for industrial control boards where deterministic 10ns timing and instant-on EEPROM configuration are required. Its MultiVolt I/O lets it interface to legacy 5V sensors and 3.3V microcontrollers on the same PCB without level shifters. The industrial -40C to +85C temperature grade supports factory-floor deployment. With 227.3 MHz counter frequency, it can drive high-speed encoder and PWM control loops while the JTAG ISP interface enables in-field firmware updates during commissioning.
Recommandé
Peripheral Bus Interface Bridging
The 68 user I/O pins of the EPM7256AQI208-10 enable direct bridging between legacy peripheral buses (ISA, VME, PC/104) and modern 3.3V processor buses, eliminating the need for multiple discrete glue-logic chips. Its 10ns pin-to-pin delay ensures deterministic bus-arbitration and chip-select generation timing across the full industrial temperature range. The non-volatile EEPROM configuration means no boot-PROM is required, reducing BOM cost and board footprint in embedded computing designs.
Recommandé
Address Decoding and Chip-Select Generation
The EPM7256AQI208-10 is well suited to generating chip-select signals for memory-mapped peripherals in 16-bit and 32-bit embedded systems, with 256 macrocells providing ample capacity for complex address maps. Its 10ns propagation delay matches the access-time budgets of most SRAM, Flash, and peripheral devices used in industrial controllers. The MultiVolt I/O permits direct interface to 5V memory banks from a 3.3V processor without external buffers, simplifying board layout.
Recommandé
Motor Control State Machines
The EPM7256AQI208-10's deterministic timing and 227.3 MHz internal counter frequency enable precise PWM and stepper-motor state-machine implementation in industrial motor-control applications. Its 68 I/O pins easily accommodate multi-axis encoder inputs, Hall-sensor feedback, and PWM outputs for 3-phase inverter control. The industrial temperature range supports under-hood and factory-cabinet environments where ambient temperatures can exceed 70C during operation.
Recommandé
Legacy Telecom Backplane Glue Logic
Telecom backplanes often require 5V-tolerant I/O and deterministic timing for TDM bus arbitration and clock-distribution functions - exactly the role the EPM7256AQI208-10 was designed for. Its 256 macrocells handle full backplane address decoding while 68 I/O pins support multiple TDM framers and serializers. The JTAG ISP interface allows board-level diagnostics without removing the part, critical for high-availability telecom infrastructure.
Recommandé
Microcontroller I/O Expansion
The EPM7256AQI208-10 can serve as a high-density I/O expander for microcontrollers that lack sufficient GPIO pins, providing 68 additional user I/O with deterministic read/write timing. The JTAG interface allows firmware updates without reprogramming the host microcontroller, simplifying field maintenance. MultiVolt I/O enables direct interface to 5V microcontrollers or 3.3V ARM Cortex-M devices on the same board.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour EPM7256AQI208-10 — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | EPM7256AQC208-7 | EPM7256AEQC208-5N | EPM3256AQC208-10N | EPM7256AEQI208-7N |
|---|---|---|---|---|---|
| Package | PQFP-208 | PQFP-208 (same) | PQFP-208 (same) | PQFP-208 (same) | PQFP-208 (same) |
| Brand | Intel (formerly Altera) | Intel (formerly Altera) | Intel (formerly Altera) | Intel (formerly Altera) | Intel (formerly Altera) |
| Pin-to-Pin Delay | 10 ns | 7 ns (-30%) | 5 ns (-50%) | 10 ns (same) | 7 ns (-30%) |
| Macrocells | 256 | 256 (same) | 256 (same) | 256 (same) | 256 (same) |
| User I/O Pins | 68 | 68 (same) | 68 (same) | 68 (same) | 68 (same) |
| Operating Temperature | -40C to +85C (industrial) | 0C to +70C (commercial) | 0C to +70C (commercial) | 0C to +70C (commercial) | -40C to +85C (industrial) |
| Maximum Counter Frequency | 227.3 MHz | 285.7 MHz | 333.3 MHz | 227.3 MHz | 285.7 MHz |
| Core Voltage | 3.3 V | 3.3 V | 3.3 V | 3.3 V | 3.3 V |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND |
| Family | MAX 7000A | MAX 7000A | MAX 7000AE | MAX 3000A | MAX 7000AE |
Principaux différenciateurs
- Industrial temperature range with full -40C to +85C operation (vs EPM7256AQC208-7)
- Largest macrocell density in MAX 7000A PQFP-208 line (vs EPM7256AETI144-7N)
- MultiVolt I/O for 5V/3.3V/2.5V mixed-voltage interfacing (vs EPM3256AQC208-10N)
Notes de conception
The EPM7256AQI208-10 requires a stable 3.3V core supply (VCC) and four independent I/O bank supplies (VCCIO1-VCCIO4) which may be set to 2.5V, 3.3V, or 5.0V depending on the logic family being interfaced. Decoupling: place one 0.1uF ceramic capacitor near each VCC and VCCIO pin, plus a bulk 10-100uF tantalum or polymer capacitor at the board's power entry. Estimated: with 68 I/O toggling at 10 MHz and 50% utilization, I/O current draw is approximately 100-200 mA on the VCCIO rails; budget the 3.3V regulator accordingly. During JTAG ISP, all VCCIO rails must remain stable to prevent programming errors.
The PQFP-208 plastic package has a typical theta-JA of approximately 25-35 C/W depending on PCB copper area. Estimated: at 100 mA I/O current with all banks driving 5V outputs into 50pF loads at 10 MHz, internal dissipation can reach 0.5-1.0W, producing a 12-35C junction-temperature rise above ambient at room temperature. For full industrial -40C to +85C operation, ensure the design includes at least 4 square inches of ground-plane copper under the PQFP to keep junction temperatures within spec. Avoid placing the CPLD near board-edge heat sinks or other high-power devices.
Place the EPM7256AQI208-10 close to its associated microcontrollers or bus devices to minimize signal-trace lengths; keep high-speed GCLK traces under 25mm to avoid reflections. Use controlled-impedance routing (typically 50-ohm microstrip or stripline) for GCLK1, GCLK2, and any clock-distribution outputs above 50 MHz. Separate analog and digital ground planes if mixing 5V analog signals into the I/O banks, joining them only at a single star-point near the CPLD's GND pins. Reserve JTAG pins (TDI, TMS, TCK, TDO) on a dedicated header or test pad for in-system programming access.
Do not exceed the absolute-maximum VCCIO voltage of 5.5V on any I/O bank or the part may suffer permanent damage. Note that the 10ns pin-to-pin delay is the worst-case over the full industrial temperature range; designs targeting the highest commercial-temperature timing margins should specify the 7ns -7 speed grade (EPM7256AQC208-7). When migrating from commercial-grade MAX 7000A parts, ensure the new device's MultiVolt I/O bank voltages match the legacy circuit - the 'E' suffix variants (e.g., EPM7256AEQC208-5N) have enhanced MultiVolt features that differ subtly from the non-'E' parts. Always confirm pinout compatibility before substituting between PQFP-208 and FineLine BGA packages.
Informations de conformité
RoHS-compliant per distributor listings (Altera-Price.com confirms lead-free / RoHS status). AEC-Q100 automotive qualification not specified - this is an industrial-grade part. REACH and halogen-free status not explicitly stated in verified data; consult Intel product declaration for confirmation.
