Cypress CY2291 manual Pinouts, Pin Definitions Name Pin Number Description

CY2291

Pinouts

Figure 1. CY2291- 20-pin SOIC
32XOUT	1	20	32XIN
32K	2	19	VBATT
CLKC	3	18	SHUTDOWN/OE
VDD	4	17	S2/SUSPEND
GND	5	16	VDD
XTALIN	6	15	S1
XTALOUT	7	14	S0
XBUF	8	13	CLKF
CLKD	9	12	CLKA
CPUCLK	10	11	CLKB

Pin Definitions

Name	Pin Number	Description
32XOUT	1	32.768-kHz crystal feedback.
32K	2	32.768-kHz output (always active if VBATT is present).
CLKC	3	Configurable clock output C.
VDD	4, 16	Voltage supply.
GND	5	Ground.
XTALIN[1]	6	Reference crystal input or external reference clock input.
XTALOUT[1, 2]	7	Reference crystal feedback.
XBUF	8	Buffered reference clock output.
CLKD	9	Configurable clock output D.
CPUCLK	10	CPU frequency clock output.
CLKB	11	Configurable clock output B.
CLKA	12	Configurable clock output A.
CLKF	13	Configurable clock output F.
S0	14	CPU clock select input, bit 0.
S1	15	CPU clock select input, bit 1.
S2/SUSPEND	17	CPU clock select input, bit 2. Optionally enables suspend feature when LOW.[3]
SHUTDOWN/OE	18	Places outputs in three-state[4]condition and shuts down chip when LOW. Optionally, only
		places outputs in three-state[4]condition and does not shut down chip when LOW.
VBATT	19	Battery supply for 32.768-kHz circuit.
32XIN	20	32.768-kHz crystal input.

Notes

1.For best accuracy, use a parallel-resonant crystal, CLOAD ≈ 17 pF or 18 pF.

2.Float XTALOUT pin if XTALIN is driven by reference clock (as opposed to crystal).

3.Please refer to application note “Understanding the CY2291, CY2292 and CY2295” for more information.

4.The CY2291 has weak pull downs on all outputs (except 32K). Hence, when a three-state condition is forced on the outputs, the output pins are pulled LOW.

Document #: 38-07189 Rev. *C Page 2 of 12

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