LM2917N-14 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – Frequency to Voltage Converter

February 1995
LM2907 LM2917 Frequency to Voltage Converter
General Description
The LM2907 LM2917 series are monolithic frequency to
voltage converters with a high gain op amp comparator de-
signed to operate a relay lamp or other load when the input
frequency reaches or exceeds a selected rate The tachom-
eter uses a charge pump technique and offers frequency
doubling for low ripple full input protection in two versions
(LM2907-8 LM2917-8) and its output swings to ground for a
zero frequency input
Advantages
Y _{Output swings to ground for zero frequency input}
Y _{Easy to use VOUT} e _fIN c _VCC c _R1 c _C1
Y _{Only one RC network provides frequency doubling}
Y _{Zener regulator on chip allows accurate and stable fre-}
quency to voltage or current conversion (LM2917)
Features
Y _{Ground referenced tachometer input interfaces directly}
with variable reluctance magnetic pickups
Y _{Op amp comparator has floating transistor output}
Y _{50 mA sink or source to operate relays solenoids me-}
ters or LEDs
Y _{Frequency doubling for low ripple}
Y _{Tachometer has built-in hysteresis with either differen-}
tial input or ground referenced input
Y _{Built-in zener on LM2917}
Y g_{0 3% linearity typical}
Y _{Ground referenced tachometer is fully protected from}
damage due to swings above V_CC and below ground
Applications
Y _{Over under speed sensing}
Y _{Frequency to voltage conversion (tachometer)}
Y _Speedometers
Y _{Breaker point dwell meters}
Y _{Hand-held tachometer}
Y _{Speed governors}
Y _{Cruise control}
Y _{Automotive door lock control}
Y _{Clutch control}
Y _{Horn control}
Y _{Touch or sound switches}
Block and Connection Diagrams Dual-In-Line and Small Outline Packages Top Views
TL H 7942 – 1
Order Number LM2907M-8 or LM2907N-8
See NS Package Number M08A or N08E
TL H 7942 – 2
Order Number LM2917M-8 or LM2917N-8
See NS Package Number M08A or N08E
Order Number LM2907N
See NS Package Number N14A
TL H 7942 – 3
C1995 National Semiconductor Corporation TL H 7942
TL H 7942 – 4
Order Number LM2917M or LM2917N
See NS Package Number M14A or N14A
RRD-B30M115 Printed in U S A