Datasheet

MCP2122
DS21894C-page 26 Preliminary © 2007 Microchip Technology Inc.
FIGURE 4-8: RXIR AND RX WAVEFORMS
TABLE 4-8: RXIR REQUIREMENTS
AC Characteristics
Standard Operating Conditions (unless otherwise specified)
Operating Temperature: –40°C ≤ T
A ≤ +125°C (Extended)
Operating Voltage VDD range is described in
Section 4.1 “DC Characteristics”.
Param.
No.
Sym Characteristic Min Typ
(1)
Max Units Conditions
IR101A ERXIRBIT RXIR Error — — ± 2 % Note 2, 3
IR101B ERXBIT Host UART RX Error — 0 — % Note 2, 4
IR103 T
TXRF RX pin rise time and fall
time
——25ns
IR110 T
RXBIT Receive (RX pin) Bit Rate 16 — 16 TXCLK
IR130 T
RXIRL2RXH RXIR Low AND 16XCLK
edge (↓ or ↑) to RX falling
edge (↓)
—4—TXCLK At 115,200 baud
—3—T
XCLK At 9600 baud
IR131A T
RXIRPW RXIR pulse width 1.41 — 3 TXCLK µs
IR132 T
RXIRP RXIR bit period
(1)
—16—TXCLK
IR133 TRXIRJ 16XCLK to RXIR jitter — — 1 TXCLK Note 2
IR134 T
RXSKW 16XCLK to RX skew — — 2.5 µs
IR135 T
RXPDFIL RXIR Filter 0.7 — 1.4 µs Note 5
Note 1: Data in the Typical (“Typ”) column is at 5V, +25°C, unless otherwise stated. These parameters are for
design guidance only and are not tested.
2: These parameters (shaded) are characterized but are not tested. These values should be used for design
guidance only.
3: The RXIR pin operation is asynchronous to the 16XCLK pin. This is the error from the desired baud rate for
the system.
4: The RX pin operation is synchronous to the 16XCLK pin. Any error present on the 16XCLK pin
(Parameter 1C) will be refelected on the RX pin.
5: The minimum specification ensures that ALL pulses less then this pulse width are rejected, the maximum
specification ensures that ALL pulses greater than this pulse width are never rejected, and pulse widths
between these may or may not be rejected.
16XCLK
RX
RXIR
0100 01
IR131A
IR110
IR132 IR132 IR132 IR132 IR132 IR132
Bit Bit Bit Bit Bit ...
IR133
IR134
Note: Refer to Figure 4-2 for load conditions.
IR103
IR103
IR132 IR132 IR132 IR132 IR132 IR132
IR130