Datasheet

LM12454, LM12458, LM12H458
www.ti.com SNAS079A –MAY 2004–REVISED FEBRUARY 2006
DIGITAL TIMING CHARACTERISTICS
(1) (2) (3)
The following specifications apply to the LM12454, LM12458, and LM12H458 for V
A
+ = V
D
+ = 5V, t
r
= t
f
= 3 ns, and C
L
= 100
pF on data I/O, INT and DMARQ lines unless otherwise specified. Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other
limits T
A
= T
J
= 25°C.
Symbol (See
Figure 7
Parameter Conditions Typical
(4)
Limits
(5)
Units
Figure 40
Figure 42)
1, 3 CS or Address Valid to ALE Low Set-Up Time 40 ns (min)
2, 4 CS or Address Valid to ALE Low Hold Time 20 ns (min)
5 ALE Pulse Width 45 ns (min)
6 RD High to Next ALE High 35 ns (min)
7 ALE Low to RD Low 20 ns (min)
8 RD Pulse Width 100 ns (min)
9 RD High to Next RD or WR Low 100 ns (min)
10 ALE Low to WR Low 20 ns (min)
11 WR Pulse Width 60 ns (min)
12 WR High to Next ALE High 75 ns (min)
13 WR High to Next RD or WR Low 140 ns (min)
14 Data Valid to WR High Set-Up Time 40 ns (min)
15 Data Valid to WR High Hold Time 30 ns (min)
10 ns (min)
16 RD Low to Data Bus Out of TRI-STATE 40
70 ns (max)
10 ns (min)
17 RD High to TRI-STATE R
L
= 1 kΩ 30
110 ns (max)
10 ns (min)
18 RD Low to Data Valid (Access Time) 30
80 ns (max)
20 Address Valid or CS Low to RD Low 20 ns (min)
21 Address Valid or CS Low to WR Low 20 ns (min)
19 Address Invalid from RD or WR High 10 ns (min)
10 ns (min)
22 INT High from RD Low 30
60 ns (max)
10 ns (min)
23 DMARQ Low from RD Low 30
60 ns (max)
(1) Two on-chip diodes are tied to each analog input through a series resistor, as shown below. Input voltage magnitude up to 5V above
V
A
+ or 5V below GND will not damage the LM12454 or the LM12(H)458. However, errors in the A/D conversion can occur if these
diodes are forward biased by more than 100 mV. As an example, if V
A
+ is 4.5 V
DC
, full-scale input voltage must be ≤4.6 V
DC
to ensure
accurate conversions. See Figure 3
(2) V
A
+ and V
D
+ must be connected together to the same power supply voltage and bypassed with separate capacitors at each V
+
pin to
assure conversion/comparison accuracy.
(3) Accuracy is ensured when operating at f
CLK
= 5 MHz for the LM12454/8 and f
CLK
= 8 MHz for the LM12H458.
(4) Typical figures are at T
A
= 25°C and represent most likely parametric norm.
(5) Limits are to AOQL (Average Output Quality Level).
Figure 3.
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Product Folder Links: LM12454 LM12458 LM12H458