LM4985TM datasheet(9/29 Pages) NSC

9 / 29 page

Electrical Characteristics V

DD = 2.5V (Notes 1, 2) (Continued)

The following specifications apply for R

L =16

Ω, f = 1kHz, and C

B = 4.7µF unless otherwise specified. Limits apply to TA =

25˚C.

Symbol

Parameter

Conditions

LM4985

Units

(Limits)

Typ

(Note 6)

Limit

(Notes 7,

VMAX

Maximum Gain

Code = 11111

∆A

Gain Accuracy per Step

18dB

≥ A

≥ –44dB

–44dB

≥ A

V > –76dB

± 0.5

± 1.0

Output Offset Voltage

OCL

LOAD =32

Ω

IN =ACGND

2.0

Note 1: All voltages are measured with respect to the GND pin unless otherwise specified.

Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

functional but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which

guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit

is given, however, the typical value is a good indication of device performance.

Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX,

θJA, and the ambient temperature, TA. The maximum

allowable power dissipation is PDMAX =(TJMAX -TA)/ θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4985, see power derating

currents for more information.

Note 4: Human Body Model: 100pF discharged through a 1.5k

Ω resistor.

Note 5: Machine Model: 200pF

≤ Cmm ≤ 220pF discharged through all pins.

Note 6: Typicals are measured at 25˚C and represent the parametric norm.

Note 7: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 8: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.

Note 9: 10

Ω terminated input.

Note 10: The LDA10A package has its exposed-DAP soldered to an exposed 1.2in2 area of 1oz. Printed circuit board copper.

Note 11: The wake-up time (TWU) is calculated using the following formula; TWU =[CBYPASS (VDD)/2(IBYPASS)] + 40ms.

External Components Description (Figure 2)

Components

Functional Description

Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a

high-pass filter with R

i at fc = 1/(2

πR

iCi). Refer to the section Proper Selection of External Components, for

an explanation of how to determine the value of C

Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing

section for information concerning proper placement and selection of the supply bypass capacitor.

Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of Proper

Components, for information concerning proper placement and selection of C

Output coupling capacitor which blocks the DC voltage at the amplifier’s output. Forms a high pass filter with

L at fo = 1/(2

πR

LCo)

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