The ISO/IEC 7816 smart card contact interface defines eight contacts, designated C1 to C8, for communication between an integrated-circuit card and a reader. This page shows the ISO 7816 signal assignment placed in the AFNOR transitional contact-field position — a location adopted for compatibility with the existing French magnetic-stripe card standard, placing the contact block in the upper-left area of the card face, as distinct from the lower-right position defined in ISO/IEC 7816-2. The contact assignments (C1 = VCC, C2 = RST, C3 = CLK, C5 = GND, C6 = VPP, C7 = I/O) are governed by ISO/IEC 7816-3; in the original 1989/1997 editions, C4 and C8 were reserved for future use. The standard was first published in 1988 and was widely deployed in French telephone cards (Télécarte) from 1983 onwards.
CONNECTOR at the card
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | +5 VDC |
| 2 | RESET | Reset |
| 3 | CLOCK | Clock |
| 4 | n/c | Not connected |
| 5 | GND | Ground |
| 6 | n/c | Not connected |
| 7 | I/O | In/Out |
| 8 | n/c | Not connected |
Signals
- C1 / VCC — power supply input; 5 V (Class A: 4.5–5.5 V); later standards added Class B (3 V) and Class C (1.8 V)
- C2 / RST — reset signal supplied by the interface device; used to initiate the Answer to Reset sequence
- C3 / CLK — clock signal provided by the interface device; initial frequency 1 MHz to 5 MHz during Answer to Reset
- C4 — not connected in the original ISO/IEC 7816-3 (1997) implementation shown here; subsequently designated AUX1 by ISO/IEC 7816-2/Amd.1:2004 and used for USB D+ in USB-ICC cards per ISO/IEC 7816-12:2005
- C5 / GND — ground reference voltage
- C6 / VPP — programming voltage input for internal non-volatile memory; originally up to 21 V on early EPROM cards, nominal 5 V idle; deprecated for external supply by ISO/IEC 7816-3:2006 and repurposed as SPU (Standard/Proprietary Use), commonly carrying SWP (Single Wire Protocol) for NFC
- C7 / I/O — serial data input/output; half-duplex; mark/high (State Z) when in reception mode, space/low (State A) when driven by transmitter
- C8 — not connected in the original ISO/IEC 7816-3 (1997) implementation shown here; subsequently designated AUX2 by ISO/IEC 7816-2/Amd.1:2004 and used for USB D- in USB-ICC cards per ISO/IEC 7816-12:2005
Notes
The AFNOR transitional position places the two-column contact block in the upper-left area of the card front surface; the ISO/IEC 7816-2 (1999/2007) standard position places the same block in the lower-right area. The physical contact locations differ, but the C1–C8 signal assignments are identical. The minimum rectangular contact surface per contact is 2 mm wide by 1.7 mm high, and contacts must not protrude more than 0.1 mm above or below the card surface.
Each contact must be electrically isolated from all others. Electrical resistance between any two points on a single contact must not exceed 0.5 Ω at currents from 50 µA to 300 mA. The card must withstand 1 000 bending cycles (2 cm deflection on the long axis, 1 cm on the short axis) without cracking or malfunction.
Activation sequence: RST held low, then VCC powered, I/O placed in reception mode, VPP raised to idle, CLK provided. Deactivation is the reverse: RST to low, CLK to low, VPP inactive, I/O to State A, VCC off.
References
- ISO/IEC 7816-2:2007 — Identification cards — Integrated circuit cards — Part 2: Dimensions and location of the contacts
- ISO/IEC 7816-2:1999/Amd 1:2004 — Assignment of contacts C4 and C8
- ISO/IEC 7816-12:2005 — Cards with contacts — USB electrical interface and operating procedures
- ISO/IEC 7816-3:2006 — Cards with contacts — Electrical interface and transmission protocols