PCF2127
Accurate RTC with integrated quartz crystal for industrial
applications
Rev. 8 — 19 December 2014
Product data sheet
1. General description
The PCF2127 is a CMOS
1
Real Time Clock (RTC) and calendar with an integrated
Temperature Compensated Crystal (Xtal) Oscillator (TCXO) and a 32.768 kHz quartz
crystal optimized for very high accuracy and very low power consumption. The PCF2127
has 512 bytes of general-purpose static RAM, a selectable I
2
C-bus or SPI-bus, a backup
battery switch-over circuit, a programmable watchdog function, a timestamp function, and
many other features.
For a selection of NXP Real-Time Clocks, see
Table 94 on page 89
2. Features and benefits
UL Recognized Component
Operating temperature range from
40 C
to +85
C
Temperature Compensated Crystal Oscillator (TCXO) with integrated capacitors
Typical accuracy:
PCF2127AT:
3
ppm from
15 C
to +60
C
PCF2127T:
3
ppm from
30 C
to +80
C
Integration of a 32.768 kHz quartz crystal and oscillator in the same package
Provides year, month, day, weekday, hours, minutes, seconds, and leap year
correction
512 bytes of general-purpose static RAM
Timestamp function
with interrupt capability
detection of two different events on one multilevel input pin (for example, for tamper
detection)
Two line bidirectional 400 kHz Fast-mode I
2
C-bus interface
3 line SPI-bus with separate data input and output (maximum speed 6.5 Mbit/s)
Battery backup input pin and switch-over circuitry
Battery backed output voltage
Battery low detection function
Extra power fail detection function with input and output pins
Power-On Reset Override (PORO)
Oscillator stop detection function
Interrupt output (open-drain)
1.
The definition of the abbreviations and acronyms used in this data sheet can be found in
Section 21.
NXP Semiconductors
PCF2127
Accurate RTC with integrated quartz crystal for industrial applications
Programmable 1 second or 1 minute interrupt
Programmable watchdog timer with interrupt
Programmable alarm function with interrupt capability
Programmable square wave output pin
Programmable countdown timer with interrupt
Clock operating voltage: 1.8 V to 4.2 V
Low supply current: typical 0.70
A
at V
DD
= 3.3 V
3. Applications
Electronic metering for electricity, water, and gas
Precision timekeeping
Access to accurate time of the day
GPS equipment to reduce time to first fix
Applications that require an accurate process timing
Products with long automated unattended operation time
4. Ordering information
Table 1.
Ordering information
Package
Name
PCF2127AT
PCF2127T
SO20
SO16
Description
plastic small outline package; 20 leads;
body width 7.5 mm
plastic small outline package; 16 leads;
body width 7.5 mm
Version
SOT163-1
SOT162-1
Type number
4.1 Ordering options
Table 2.
Ordering options
Orderable part number Sales item
(12NC)
PCF2127AT/2Y
PCF2127T/2Y
935299867518
935299866518
Delivery form
tape and reel, 13 inch, dry pack
tape and reel, 13 inch, dry pack
IC
revision
2
2
Product type number
PCF2127AT/2
PCF2127T/2
5. Marking
Table 3.
Marking codes
Marking code
PCF2127AT
PCF2127T
Product type number
PCF2127AT/2
PCF2127T/2
PCF2127
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet
Rev. 8 — 19 December 2014
2 of 100
NXP Semiconductors
PCF2127
Accurate RTC with integrated quartz crystal for industrial applications
6. Block diagram
Fig 1.
Block diagram of PCF2127
PCF2127
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet
Rev. 8 — 19 December 2014
3 of 100
NXP Semiconductors
PCF2127
Accurate RTC with integrated quartz crystal for industrial applications
7. Pinning information
7.1 Pinning
Top view. For mechanical details, see
Figure 59.
Fig 2.
Pin configuration for PCF2127AT (SO20)
Top view. For mechanical details, see
Figure 59.
Fig 3.
Pin configuration for PCF2127T (SO16)
Fig 4.
Position of the stubs from the package assembly process
PCF2127
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet
Rev. 8 — 19 December 2014
4 of 100
NXP Semiconductors
PCF2127
Accurate RTC with integrated quartz crystal for industrial applications
After lead forming and cutting, there remain stubs from the package assembly process.
These stubs are present at the edge of the package as illustrated in
Figure 4.
The stubs
are at an electrical potential. To avoid malfunction of the PCF2127, it has to be ensured
that they are not shorted with another electrical potential (e.g. by condensation).
7.2 Pin description
Table 4.
Pin description of PCF2127
Input or input/output pins must always be at a defined level (V
SS
or V
DD
) unless otherwise specified.
Symbol
SCL
SDI
SDO
SDA/CE
IFS
Pin
PCF2127AT
1
2
3
4
5
PCF2127T
1
2
3
4
5
combined serial clock input for both I
2
C-bus and SPI-bus
serial data input for SPI-bus
connect to pin V
SS
if I
2
C-bus is selected
serial data output for SPI-bus, push-pull
combined serial data input and output for the I
2
C-bus and
chip enable input (active LOW) for the SPI-bus
interface selector input
connect to pin V
SS
to select the SPI-bus
connect to pin BBS to select the I
2
C-bus
TS
CLKOUT
V
SS
n.c.
TEST
PFO
PFI
RST
INT
BBS
V
BAT
V
DD
6
7
8
9 to 12
13
14
15
16
17
18
19
20
6
7
8
-
9
10
11
12
13
14
15
16
timestamp input (active LOW) with 200 k internal pull-up
resistor (R
PU
)
clock output (open-drain)
ground supply voltage
not connected; do not connect; do not use as feed through
do not connect; do not use as feed through
power fail output (open-drain; active LOW)
power fail input
reset output (open-drain; active LOW)
interrupt output (open-drain; active LOW)
output voltage (battery backed)
battery supply voltage (backup)
connect to V
SS
if battery switch-over is not used
supply voltage
Description
PCF2127
All information provided in this document is subject to legal disclaimers.
© NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet
Rev. 8 — 19 December 2014
5 of 100
