3478A

Keysight Technologies (Agilent HP)Multimeters

The Keysight/Agilent/HP 3478A is a highly reliable 5.5-digit benchtop and system digital multimeter equipped with a standard HP-IB (GPIB) interface. It is designed for precise measurements of DC and AC voltage, DC and AC current, and 2-wire or 4-wire resistance, featuring electronic calibration and switchable front/rear input terminals.

Current Measurement Electronic Testing Resistance Measurement Voltage Measurement

Specifications

General

Parameter	Value
Interfaces	HP-IB (IEEE-488.1)
Display	12-character Liquid Crystal Display (LCD) with integrated annunciators
Ranging Modes	Auto and Manual
Power-on Self Test	Yes

Physical

Parameter	Value
Operating Temperature	0 to 55 °C
Dimensions (W×H×D)	212.3 mm W × 88.9 mm H × 275.6 mm D
Weight	3.0 kg

DC Voltage

Parameter	Value
DCV Ranges	30 mV, 300 mV, 3 V, 30 V, 300 V
DCV Maximum Resolution	100 nV (on 30 mV range)
DCV Input Resistance (≤ 3 V Ranges)	> 10 GΩ
DCV Input Resistance (30 V and 300 V Ranges)	10 MΩ ± 1%
DCV Maximum Input Voltage	300 V DC or peak AC (HI to LO)
Input Bias Current	< 20 pA at 25 °C

AC Voltage

Parameter	Value
ACV Ranges	300 mV, 3 V, 30 V, 300 V
ACV Measurement Type	True RMS (AC-coupled)
ACV Frequency Range	20 Hz to 100 kHz
ACV Input Impedance	1 MΩ ± 1% shunted by < 60 pF
ACV Maximum Input Voltage	300 V RMS, 450 V peak
ACV Maximum Resolution	1 μV (on 300 mV range)
ACV Crest Factor	4:1 at full scale

DC Current

Parameter	Value
DCI Ranges	300 mA, 3 A
DCI Maximum Resolution	1 μA (on 300 mA range)
DCI Protection Fuse	3 A, 250 V (rear panel)
DCI Maximum Continuous Input	3 A
DCI Burden Voltage (300 mA Range)	< 0.3 V
DCI Burden Voltage (3 A Range)	< 1.0 V

AC Current

Parameter	Value
ACI Ranges	300 mA, 3 A
ACI Measurement Type	True RMS (AC-coupled)
ACI Maximum Resolution	1 μA (on 300 mA range)
ACI Frequency Range	20 Hz to 20 kHz
ACI Protection Fuse	3 A, 250 V
ACI Burden Voltage (300 mA Range)	< 0.3 V
ACI Burden Voltage (3 A Range)	< 1.0 V

Resistance

Parameter	Value
Ohms Measurement Types	2-wire and 4-wire ohms
Ohms Ranges	30 Ω, 300 Ω, 3 kΩ, 30 kΩ, 300 kΩ, 3 MΩ, 30 MΩ
Ohms Maximum Resolution	100 μΩ (on 30 Ω range)
Ohms Test Current (30 Ω, 300 Ω Ranges)	1 mA
Ohms Test Current (3 kΩ Range)	1 mA
Ohms Test Current (30 kΩ Range)	100 μA
Ohms Test Current (300 kΩ Range)	10 μA
Ohms Test Current (3 MΩ Range)	1 μA
Ohms Test Current (30 MΩ Range)	100 nA
Ohms Input Protection	Protected to 250 V RMS
Max. Lead Resistance (4-wire ohms)	100 Ω in any lead (10 Ω on 30 Ω range)
Ohms Open Circuit Voltage	< 6.5 V

Measurement Rates and Performance

Parameter	Value
Display Resolution Modes	3.5, 4.5, or 5.5 digits
Maximum Reading Rate (3.5 digits)	71 readings per second (at 60 Hz)
Maximum Reading Rate (4.5 digits)	33 readings per second (at 60 Hz)
Maximum Reading Rate (5.5 digits)	1.4 readings per second (at 60 Hz)
Integration Time / Power Line Cycles (5.5 digits)	10 NPLC
Integration Time / Power Line Cycles (4.5 digits)	1 NPLC
Integration Time / Power Line Cycles (3.5 digits)	0.1 NPLC
A/D Converter Technology	Multi-slope II integrating A/D

Noise and Rejection

Parameter	Value
Normal Mode Rejection Ratio (NMRR)	> 80 dB at 50/60 Hz ±0.1% (in 5.5-digit mode)
Common Mode Rejection Ratio (CMRR) DC	> 140 dB at DC (with 1 kΩ imbalance in LO)
Common Mode Rejection Ratio (CMRR) AC	> 120 dB at 50/60 Hz (with 1 kΩ imbalance in LO)

System and Interface Configuration

Parameter	Value
HP-IB Interface Standard	IEEE-488.1 compliant
HP-IB Capability Codes	SH1, AH1, T5, TE0, L4, LE0, SR1, RL1, PP0, DC1, DT1, C0, E1
HP-IB Address Selection	Rear-panel DIP switch-selectable
Calibration Method	Electronic, from front panel or over HP-IB (no internal hardware adjustments)
Calibration Security Lock	Rear panel hardware slide switch
Maximum Common Mode Voltage	500 V peak (LO to chassis ground)

Math and Control Functions

Parameter	Value
Front/Rear Input Switching	No rear input terminals / Front panel inputs only
Trigger Modes	Internal, External, Hold, Fast (bypasses settling delay)

Physical and Environmental

Parameter	Value
Storage Temperature Range	-40 °C to +75 °C
Warm-up Time	1 hour to rated specifications
Relative Humidity Limits	Up to 95% RH at 40 °C
Form Factor	Half-rack width benchtop / system cabinet

Power Requirements

Parameter	Value
AC Input Frequency Range	48 Hz to 66 Hz
AC Input Voltage Settings	100 V / 120 V / 220 V / 240 V AC ±10%
Power Consumption	15 VA maximum
Line Frequency	48 Hz to 66 Hz
Line Fuse	0.15 A @ 115 V / 0.08 A @ 230 V (slow-blow)

DC Voltage Accuracy

Parameter	Value
DCV 1-Year Accuracy (3 V Range)	±(0.0035% of reading + 2 counts) (at 5.5 digits, 23°C ± 5°C)
DCV 1-Year Accuracy (30 V / 300 V Ranges)	±(0.004% of reading + 2 counts) / ±(0.0045% of reading + 2 counts) (at 5.5 digits, 23°C ± 5°C)
DCV 1-Year Accuracy (300 mV Range)	±(0.005% of reading + 4 counts) (at 5.5 digits, 23°C ± 5°C)

AC Voltage Accuracy

Parameter	Value
ACV 1-Year Accuracy (45 Hz - 20 kHz)	±(0.16% of reading + 110 counts) (3 V to 300 V ranges, at 5.5 digits, 23°C ± 5°C)

Resistance Accuracy

Parameter	Value
Ohms 1-Year Accuracy (3 kΩ to 300 kΩ Ranges)	±(0.011% of reading + 2 counts) (at 5.5 digits, 23°C ± 5°C)
Ohms 1-Year Accuracy (30 Ω Range)	±(0.012% of reading + 35 counts) (with Null, at 5.5 digits, 23°C ± 5°C)

DC Current Accuracy

Parameter	Value
DCI 1-Year Accuracy (300 mA Range)	±(0.15% of reading + 20 counts) (at 5.5 digits, 23°C ± 5°C)
DCI 1-Year Accuracy (3 A Range)	±(0.15% of reading + 10 counts) (at 5.5 digits, 23°C ± 5°C)

AC Current Accuracy

Parameter	Value
ACI 1-Year Accuracy (45 Hz - 20 kHz)	±(0.8% of reading + 120 counts) (300 mA range, at 5.5 digits, 23°C ± 5°C)

Input Protection

Parameter	Value
DCV/ACV Input Protection	300 V rms or 450 V peak continuous on all ranges

Triggering

Parameter	Value
External Trigger Input Level	TTL compatible (negative-edge triggered)
External Trigger Minimum Pulse Width	1.5 µs
Voltmeter Complete Pulse Width	~1.5 µs
Voltmeter Complete Output Level	TTL compatible (negative-going pulse)

Calibration

Parameter	Value
Calibration Storage	Internal non-volatile RAM (cal RAM) with lithium battery backup

Data Storage

Parameter	Value
Reading Storage Memory	None (direct streaming via HP-IB)

Display

Parameter	Value
Maximum Display Count	303,000 counts (except 300 V range)

Compliance

Parameter	Value
Safety Compliance	Designed to comply with IEC 348 and UL 1244

Technology

Multi-slope II integrating A/D conversion

Applications

Benchtop electronic testing and automated system measurement