Sequential PROPHET-600 - Page 74

CEM 3340 / CEM 3345
Electrical Characteristics
Application Hints
Vcc-*15V V tl
• Internal Zener T* - 20 C
7e»emeter
Mn
Tyo Max l>n.tt
frtgjtnfv Control Ri«g
*»i
500K 1
-
Exponent** Sc Me Error Un trimmed* 02
1 %
Exponents* Scale Error. Trimmed 1 005 03
%
Mu tipiier Gan Error2 00005 0000
Tempo Cenceliotion) -ISO 0 .150
Pfsm
OtC'itjtor Drift^ - t50 «200 ppm
Triangle Suffer Input Current
-
03 3
nA
Triangle W*t*forr Upper LtWf 50 5 15 V
Tnangte Waveform lower Lexer
-15 0 ♦ 15
mV
Tf• angle Waveform Symmetry
45 50 55 \
smooth waveform Upper Level 94 10.0 104 V
Sawtooth Waveform lower Level -29 0
*»
mV
Triangle Output Smh Capability
400 550 750
*A
Sawtooth Output S.nh Capability 040
800 1000
_mA
Tnengle & Serdooth Output lrr«e<S*ne* % 6S 100 150
n
h»iia Output Sourer Capability at *IOV IB 35 as mA
Souerewevr Output Lew*. CEM 3345
-16.-0 4
-1 3*0
-06.*CA
V
AVM 1 r«w? Pen Current*
%
16 35
pA
0WM Incut Voltage for 0% Suite Waft* -16 0 • 15
mV
FWM Input Voltage for 100% PuHe A»dth 46 SO 5.4 V
Input Current at Reference end
Control Current Inputt 80 200 400
nA
Tempco of Inoul 0«et Current* -10O0 0 • 10CM
pom
Offset Voftege et Reference end Control
Current inputs
-9
0 •6 mV
Herd Sync Reference Votxge -2 3 23
-21 V
Hard Sync Input Reui!*r«e 6
63 7.9
K12
Mai Capacitcy Cha'a»iDiw:ha«a» Cmiwit
400
570
800 -A
Posiliv* Supply c»”«"t
4 5 65
mA
Positiv* Supply VO 1 tag* Bang# •10 • 18
V
’**»'" ■ * Supply Volt.g. ".rg** -45 -18 V
Tbi* error repretertt the c*rcent age deference KMe fectoa pa» ^toumv
ranol ol the exponential generator mr^f ©*e* the exponent** generator current
range of 50nA to 100* A Mon of t*»* error occur* at the ^a«ge txtrem.tief
Th.i error mrrexenn the percentage rtfhfevi »n multiplier grim* at any too *nput tor
rants. yeitHrf> the rang* <>f 20 »A to 100 a*A. per »A d^lrrxi between the too
corresponding OuVDwtl
Th.i ioec rap resent i the difference between the actual tempco of the muddX** Output
wo’taga (exor med rg-.gtivc to the mai-njm output eRCurnont* and the tempco retired
topiK u»y cancel the tempco of the e«*»n*nt*al icai# factor Iq.’KTI
The multiplier output u p'oundad
for exponential ganeeator currenn leti than 10 *A above 10 *A. mpedance drops to
I the value at the h*?*ett current»« approached
With respect to the h»nj tync mput reference vOHege
For *W4 control .nputt betrvegn -1 P*d vO'tt Thq eu~gnt 4 t.fn.f.cantly r—f
for inpitt ovtvrtr of the rjnge
Current lamping res it tor required to» negative tuppiei greater than -4 %oitt
Supplies
Sine# the device can withstand
no mo»g then 24 volts between
•ts supoly P'nt. an internal
6 5 volt t 10% Zene* diode has
been provided to allow the
chip to operate off virtually any
negative supply voltage. II the
negative supply is between -4 6
and -6.0 volts, it may be con
necied directly to the negative
supply pm (pin 31. For voltages
greate* than -7.5 volts, a series
current limiting resistor must
be added between pm 3 and
the negative supolv Its value is
calculated as follows:
Rtt ' IV t£ - 7.21 / .008
Although the circuit was de
signed for a positive supply of
*15 volts, it may be operated
anywhere between *10 and *18
volts The only effect is on the
positive peak amplitude of the
output wavefoims m accordance
to the follow'ng: The triangle
peak is one third of the supply,
the sawtooth peak is two thuds
of the supply, and the pulse
peak is 1.5 volts below the
supply.
Operation of the
Temperature Compensation
Circuitry
Theesponential generatoi is
temperature compensated by
multiplying lh# current sourced
into thg frequency control pin
(pm 16 on the CEM3340. pm
17 on the CEM3346) times a
coefficient directly proportion*!
to the absolute temperature.
A» this control current is applied
to the exponential generator,
its coefficient cancels that of the
exponential generator, q/KT.
This coefficient is produced by
the tempco generator using the
tame mechanisms that create it
in the exponential generator,
cancellation it therefore nearly
perfect.
The output of the precision
multiplier (pin 14 on the 3340.
2