Rainbow Electronics DS28DG02 - Manual (Page 5)

DS28DG02: 2kb SPI EEPROM with PIO, RTC, Reset, Battery Monitor, and Watchdog
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PIN DESCRIPTION
PIN
NAME
TSSOP28 TQFN36
FUNCTION
X1 1 33 32.768kHz Crystal Connection 1 or 32.768kHz Input from TCXO
X2 2 34 32.768kHz Crystal Connection 2
RSTZ 3 36
Open-Drain Output Pin (Active Low) for V
CC
power-fail reset,
watchdog alarm, and Manual Reset Input. See Multifunction
Control/Setup Register
description for more information.
WDI 4 2
Watchdog Input Pin (Active High) . See Multifunction Control/Setup
Register description at address 134h for more information.
WDOZ 5 3
Open-Drain Output Pin (Active Low) for (user-choice) watchdog
alarm. See Multifunction Control/Setup Register description for more
information.
WPZ 6 4
Hardware Write-Protect Input Pin (Active Low) . See the SPI Interface
description for more information.
PIO0 7 5 PIO Line #0
PIO4 8 6 PIO Line #4
PIO8 9 7 PIO Line #8
GND 10, 19 9, 19 Ground Supply
PIO10 11 10 PIO Line #10
PIO6 12 11 PIO Line #6
PIO2 13 12 PIO Line #2
V
CC
14, 15 13, 15 Power Supply Input
PIO3 16 16 PIO Line #3
PIO7 17 17 PIO Line #7
PIO11 18 18 PIO Line #11
PIO9 20 21 PIO Line #9
PIO5 21 22 PIO Line #5
PIO1 22 23 PIO Line #1
ALMZ 23 24
Open-Drain Output Pin (Active Low) for RTC, battery monitor, and
(user-choice) watchdog alarms. See the Multifunction Control/Setup
Register
description for more information.
SO 24 25 SPI Serial Data Output (tristate)
SI 25 26 SPI Serial Data Input
SCK 26 28 SPI Serial Clock Input
CSZ 27 30 Chip Select Input (Active Low)
V
BAT
28 31 Backup Battery Supply for RTC and RSTZ support.
N.C. —
1, 8, 14,
20, 27,
29, 32, 35
No Connection
GND EP EP
Exposed Paddle. Solder evenly to the board’s ground plane for proper
operation. See Application Note 3273 for additional information.
OVERVIEW
The DS28DG02 features 2kb of EEPROM, 12 bidirectional PIO channels, an RTC with calendar and alarm
function, a watchdog timer, two voltage monitors with precision trip points, and three alarm/reset outputs. Each
DS28DG02 has its own unique registration number, which serves as identification of the product the device is
embedded in. All these resources are accessed through a serial SPI interface, as shown in the block diagram in
Figure 1. The SPI interface automatically adjusts to SPI modes (0,0) and (1,1). The V
CC
trip point, which controls
the power-fail reset output (RSTZ pin), is set at the factory. The user can set the battery monitor threshold and the
watchdog time-out through software. The RTC uses the common BCD format for time, calendar and day of the
week. The device can be programmed to generate an RTC alarm every second, minute, hour, or day and once a
week or once a month at a user-defined time. RTC, watchdog, and battery alarm can be individually enabled.