AN837
How to Configure a Low-Power Timer/Oscillator to Operate from Higher
Supply Voltages
1. Introduction
Low-power, low voltage CMOS timers/oscillators like the TS3001/TS3002 are specified to operate at 1 V,
consuming supply currents as low as 1 µA. While the TS3001/TS3002 has an operating VDD voltage range of
0.9 V–1.8 V, systems running from higher supply voltages can also take advantage of the low supply currents of
this micropower timer, by adding a few inexpensive transistors to the operating circuit.
In the circuit below, Q2 drops the voltage from a higher V+ voltage to supply the TS3002 at a reduced voltage. The
VBE voltage of Q1 provides a compensating voltage for the VBE of Q2, providing some temperature tracking. The
values R1 and R2 can be changed to optimize the design for other V+ voltage ranges, as shown in Table 1.
Q3, together with R5, provide an output level translation function, so that the output voltage can swing to V+ if
needed. Q3 was chosen for its low output capacitance (specified at 3 pF with VDS = 15 V; estimated at 10 pF with
VDS = 3 V). The value of R5 can be decreased to increase positive-going slew rates, at the expense of current
drawn from V+. With R5=220 k, trise = 2.2 µs during the rising edge of FOUT.
V+
2.3V-3.3V
C1
0.1µF
CR2032
coin
cell
C2
1nF
R1
1M
R2
1M
Q2
2N3904
Q1
2N3904
FOUT
BOOST
PWMOUT
VDD
RSET
GND
CSET
TS3002
R3
1M
R4
4.32M
R5
220K
(optional- for
PWM output)
FOUT
R6
220K
PWMOUT
Q4
½ CMRDM3590
CTRL
U1
C3A
10pF
C3B
10pF
Q3
½ CMRDM3590
Figure 1. TS3002 Operating from a CR2032 Coin Cell
Rev. 1.0 1/15
Copyright © 2015 by Silicon Laboratories
AN837
Smart.
Connected.
Energy-Friendly
Products
www.silabs.com/products
Quality
www.silabs.com/quality
Support and Community
community.silabs.com
Disclaimer
Silicon Laboratories intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software implementers
using or intending to use the Silicon Laboratories products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific
device, and "Typical" parameters provided can and do vary in different applications. Application examples described herein are for illustrative purposes only. Silicon Laboratories
reserves the right to make changes without further notice and limitation to product information, specifications, and descriptions herein, and does not give warranties as to the accuracy
or completeness of the included information. Silicon Laboratories shall have no liability for the consequences of use of the information supplied herein. This document does not imply
or express copyright licenses granted hereunder to design or fabricate any integrated circuits. The products must not be used within any Life Support System without the specific
written consent of Silicon Laboratories. A "Life Support System" is any product or system intended to support or sustain life and/or health, which, if it fails, can be reasonably expected
to result in significant personal injury or death. Silicon Laboratories products are generally not intended for military applications. Silicon Laboratories products shall under no
circumstances be used in weapons of mass destruction including (but not limited to) nuclear, biological or chemical weapons, or missiles capable of delivering such weapons.
Trademark Information
Silicon Laboratories Inc., Silicon Laboratories, Silicon Labs, SiLabs and the Silicon Labs logo, CMEMS®, EFM, EFM32, EFR, Energy Micro, Energy Micro logo and combinations
thereof, "the world’s most energy friendly microcontrollers", Ember®, EZLink®, EZMac®, EZRadio®, EZRadioPRO®, DSPLL®, ISOmodem ®, Precision32®, ProSLIC®, SiPHY®,
USBXpress® and others are trademarks or registered trademarks of Silicon Laboratories Inc. ARM, CORTEX, Cortex-M3 and THUMB are trademarks or registered trademarks of
ARM Holdings. Keil is a registered trademark of ARM Limited. All other products or brand names mentioned herein are trademarks of their respective holders.
Silicon Laboratories Inc.
400 West Cesar Chavez
Austin, TX 78701
USA
http://www.silabs.com
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
