General Description
The MAX5420 and MAX5421 are digitally programmable
precision voltage dividers optimized for use in digitally pro-
grammable gain amplifier configurations. The MAX5420/
MAX5421 operate from a single +5V supply or dual ±5V
supply, and consume only 3µA supply current. These
devices consist of a digitally selectable resistor array that
provides four precision noninverting gains of 1, 2, 4, and 8
for PGAs. The MAX5420 and MAX5421 achieve a resistor
ratio accuracy of 0.025% (MAX542_A), 0.09% (MAX542_B),
and 0.5% (MAX542_C). The MAX5421 includes an on-chip
matching resistor for op amp bias-current compensation.
The MAX5420 and MAX5421 are available in 8-pin and
10-pin µMAX packages. The devices are specified over
the extended temperature range (-40°C to +85°C).
Applications
General-Purpose Programmable Noninverting
Amplifiers
Programmable Instrumentation Amplifiers
Features
♦Four Precision Divider Ratios For Noninverting
Gains of 1, 2, 4, and 8 in PGAs
♦0.025%, 0.09%, or 0.5% Ratio Accuracy
Guaranteed Over -40°C to +85°C
♦On-Chip Matching Resistor for Op Amp Bias-
Current Compensation (MAX5421)
♦5V Single or ±5V Dual Supply Operation
♦Low 3µA Supply Current
♦CMOS/TTL Logic Compatible 2-Wire Parallel
Interface
♦Small 8-Pin and 10-Pin µMAX Packages
MAX5420/MAX5421
Digitally Programmable Precision
Voltage Divider for PGAs
________________________________________________________________ Maxim Integrated Products 1
L
D1D0
1
2
8
7
H
WVSS
GND
VDD
µMAX-8
TOP VIEW
3
4
6
5
MAX5420
1
2
3
4
5
10
9
8
7
6
H
W
L
MATCH_HD0
GND
VSS
VDD
MAX5421
µMAX-10
MATCH_LD1
Pin Configurations
Ordering Information
Functional Diagram
19-2230; Rev 2; 2/05
PART TEMP.
RANGE
PIN-
PACKAGE
GAIN
ACCURACY
MAX5420AEUA -40°C to +85°C 8 µMAX 0.025%
MAX5420BEUA -40°C to +85°C 8 µMAX 0.09%
MAX5420CEUA -40°C to +85°C 8 µMAX 0.5%
MAX5421AEUB -40°C to +85°C 10 µMAX 0.025%
MAX5421BEUB -40°C to +85°C 10 µMAX 0.09%
MAX5421CEUB -40°C to +85°C 10 µMAX 0.5%
DECODER
MATCH_H
MATCH_L
MAX5421 ONLY
H
VDD
W
L
GND
VSS
MAX5420
MAX5421
D0
D1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX5420/MAX5421
Digitally Programmable Precision
Voltage Divider for PGAs
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD = +5V ±5%, VSS = -5V ±5% or VSS = GND, TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VDD to GND..............................................................-0.3V to +6V
VSS to GND...............................................................+0.3V to -6V
D0, D1 to GND ...........................................-0.3V to (VDD + 0.3V)
H, L, W, MATCH_ to GND ................(VSS - 0.3V) to (VDD + 0.3V)
Input and Output Latchup Immunity.................................±50mA
Continuous Power Dissipation (TA= +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............333mW
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX542_A ±0.025
MAX542_B ±0.09
Divider Ratio Accuracy
MAX542_C ±0.5
%
H-to-L Resistance RHL (Figure 1) 15 kΩ
Input Resistance at H RH15 kΩ
VSS = -5V 300
Ratio = 1 VSS = 0 500 Ω
Input Resistance at W RW
Ratio = 2, 4, 8 8 kΩ
Capacitance at H, L, W,
MATCH_H, MATCH_L CANALOG 5pF
VSS = -5V 300
Ratio = 1 VSS = 0 500 Ω
Matching Resistor MAX5421
Ratio = 2, 4, 8 8 kΩ
DYNAMIC PERFORMANCE
Switching Time tS
V
D D
= + 5V , V
S S
= - 5V , d i g i tal i np ut 0 to + 3V ,
V
W settl es to 0.02% of fi nal val ue w i th 2p F
cap aci ti ve l oad . C i r cui t of Fi g ur e 2.
0.5 µs
DIGITAL INPUTS
Input High Voltage VIH 2.4
Input Low Voltage VIL 0.8 V
Input Leakage Current D1, D0 = VDD or GND ±1 µA
Input Capacitance 5pF
MAX5420/MAX5421
Digitally Programmable Precision
Voltage Divider for PGAs
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +5V ±5%, VSS = -5V ±5% or VSS = GND, TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
POWER SUPPLIES
Positive Supply Voltage VDD 4.75 5.25
Negative Supply Voltage VSS 0 -5.25 V
D1, D0 = VDD or GND 3 7
Positive Supply Current IDD D1, D0 = 3V 15 25 µA
D1, D0 = VDD or GND 3 7
Negative Supply Current ISS D1, D0 = 3V 15 25 µA
W, H, L, MATCH_L, MATCH_H
Voltage Range VSS VDD V
Typical Operating Characteristics
(VDD = +5V, VSS = -5V, or VSS = GND, TA= +25°C, unless otherwise noted.) (Note 1)
0.0001
0.0004
0.0007
0.0010
MAX542_A DIVIDER RATIO ACCURACY
vs. TEMPERATURE
MAX5420/21 toc01
TEMPERATURE (°C)
RATIO ACCURACY (%)
-40 -15 10 35 60 85
VH = +5V
VL = -5V
RATIO = 1
0.0030
0.0034
0.0042
0.0038
0.0046
0.0050
-40 10-15 35 60 85
MAX542_A DIVIDER RATIO ACCURACY
vs. TEMPERATURE
MAX5420/21 toc02
TEMPERATURE (°C)
RATIO ACCURACY (%)
VH = +5V
VL = -5V
RATIO = 2
0
0.001
0.003
0.002
0.004
0.005
-40 10-15 35 60 85
MAX542_A DIVIDER RATIO ACCURACY
vs. TEMPERATURE
MAX5420/21 toc03
TEMPERATURE (°C)
RATIO ACCURACY (%)
VH = +5V
VL = -5V
RATIO = 4
MAX5420/MAX5421
Digitally Programmable Precision
Voltage Divider for PGAs
4 _______________________________________________________________________________________
0
0.002
0.001
0.004
0.003
0.006
0.005
0.007
-40 10-15 35 60 85
MAX542_A DIVIDER RATIO ACCURACY
vs. TEMPERATURE
MAX5420/21 toc04
TEMPERATURE (°C)
RATIO ACCURACY (%)
VH = +5V
VL = -5V
RATIO = 8
0.0020
0.0015
0.0010
0.0005
0
-40 10-15 35 60 85
MAX542_B DIVIDER RATIO ACCURACY
vs. TEMPERATURE
MAX5420/21 toc05
TEMPERATURE (°C)
RATIO ACCURACY (%)
VH = +5V
VL = -5V
RATIO = 1
-0.0200
-0.0225
-0.0250
-0.0275
-0.0300
-40 10-15 35 60 85
MAX542_B DIVIDER RATIO ACCURACY
vs. TEMPERATURE
MAX5420/21 toc06
TEMPERATURE (°C)
RATIO ACCURACY (%)
VH = +5V
VL = -5V
RATIO = 2
-0.030
-0.035
-0.040
-0.045
-0.050
-40 10-15 35 60 85
MAX542_B DIVIDER RATIO ACCURACY
vs. TEMPERATURE
MAX5420/21 toc07
TEMPERATURE (°C)
RATIO ACCURACY (%)
VH = +5V
VL = -5V
RATIO = 4
-0.050
-0.055
-0.060
-0.065
-0.070
-40 10-15 35 60 85
MAX542_B DIVIDER RATIO ACCURACY
vs. TEMPERATURE
MAX5420/21 toc08
TEMPERATURE (°C)
RATIO ACCURACY (%)
VH = +5V
VL = -5V
RATIO = 8
0.01
0.0001
4.75 5.00 5.25
MAX542_A RATIO ACCURACY
vs. POSITIVE SUPPLY VOLTAGE
MAX5420/21 toc09
POSITIVE SUPPLY VOLTAGE (V)
RATIO ACCURACY (%)
0.001
VH = +3V, VL = 0
RATIO = 4
RATIO = 2
RATIO = 1
RATIO = 8
0.1
0.0001
4.75 5.00 5.25
MAX542_B RATIO ACCURACY
vs. POSITIVE SUPPLY VOLTAGE
MAX5420/21 toc10
POSITIVE SUPPLY VOLTAGE (V)
RATIO ACCURACY (%)
0.01
0.001
VH = +3V, VL = 0
RATIO = 2
RATIO = 1
RATIO = 4
RATIO = 8
0.01
0.0001
-5.25 -2.75 -0.25
MAX542_A RATIO ACCURACY
vs. NEGATIVE SUPPLY VOLTAGE
MAX5420/21 toc11
NEGATIVE SUPPLY VOLTAGE (V)
RATIO ACCURACY (%)
0.001
-4.00 -1.50
VH = 5V, VL = 0
RATIO = 8
RATIO = 4
RATIO = 1
RATIO = 2
0.1
0.01
0.0001
-5.25 -2.75 -0.25
MAX542_B RATIO ACCURACY
vs. NEGATIVE SUPPLY VOLTAGE
MAX5420/21 toc12
NEGATIVE SUPPLY VOLTAGE (V)
RATIO ACCURACY (%)
0.001
-4.00 -1.50
RATIO = 1
VH = 5V, VL = 0
RATIO = 8
RATIO = 2
RATIO = 4
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = -5V, or VSS = GND, TA= +25°C, unless otherwise noted.) (Note 1)
MAX5420/MAX5421
Digitally Programmable Precision
Voltage Divider for PGAs
_______________________________________________________________________________________ 5
100ns/div
VH = +5V, VL = -5V
SWITCHING TIME
(RATIO 1-TO-2)
VW
2V/div
MAX5420/21 toc13
D0, 5V/div
0
100ns/div
VH = +5V, VL = -5V
SWITCHING TIME
(RATIO 2-TO-4)
VW
1V/div
MAX5420/21 toc14
D1, 5V/div
0
100ns/div
VH = +5V, VL = -5V
SWITCHING TIME
(RATIO 4-TO-8)
VW
500mV/div
5V
MAX5420/21 toc15
D0, 5V/div
0
0
1
3
2
4
5
-40 10-15 35 60 85
SUPPLY CURRENT
vs. TEMPERATURE
MAX5420/21 toc16
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
D1, D0 = GND or VDD
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = -5V, or VSS = GND, TA= +25°C, unless otherwise noted.) (Note 1)
Note 1: For MAX542_C accuracy Typical Operating Characteristics, refer to MAX542_B accuracy Typical Operating Characteristics.
MAX5420/MAX5421
Detailed Description
The MAX5420/MAX5421 are digitally programmable pre-
cision voltage dividers for programmable-gain amplifiers.
Operationally, these devices consist of digitally selectable
precision resistor-dividers providing noninverting gains of
1, 2, 4, and 8 for PGA applications (see Functional
Diagram and Figure 1).
The MAX5420/MAX5421 achieve divider ratio accuracy of
0.025% (MAX5420A/MAX5421A), 0.09% (MAX5420B/
MAX5421B) or 0.5% (MAX5420C/MAX5421C).
The end-to-end resistance from H to L is 15kΩ. The
impedance seen at W is designed to be the same 8kΩ
for divider ratios 2, 4, and 8, ensuring excellent imped-
ance matching and constant switching times. In gain of
+1 configuration, H is internally connected to W with a
typical resistance of 500Ω.
Matching Resistor (MAX5421)
The MAX5421 includes a matching resistor to compen-
sate for offset voltage due to input bias current of the
op amp. The resistance from MATCH_H to MATCH_L,
equals the resistance seen at W for gains of 2, 4, and 8.
In the gain of +1, an internal switch connects
MATCH_H and MATCH_L. This internal switch matches
the impedance of the switch between H and W.
Digital Interface Operation
The MAX5420/MAX5421 feature a simple two-bit paral-
lel programming interface. D1 and D0 program the
divider ratio setting according to the Logic Control
Truth Table (Table 1). The digital interface is CMOS/TTL
logic compatible.
Applications Information
Programmable-Gain Amplifier
The MAX5420/MAX5421 are ideally suited for high-pre-
cision PGA applications. The typical application circuit
of Figure 3 uses the MAX5421 with matching resistor to
compensate for voltage offset due to op amp input bias
currents. Use the MAX5420 with an ultra-low input bias
current op amp such as the MAX4237 (Figure 4).
Power Supplies and Bypassing
The MAX5420/MAX5421 operate from dual ±5V sup-
plies, or a single +5V supply. For dual supplies, bypass
VDD and VSS with 0.1µF ceramic capacitors to GND.
For single supply, connect VSS to GND and bypass
VDD with a 0.1µF ceramic capacitor to GND.
Ratio RB
RA
=+1_
_
Digitally Programmable Precision
Voltage Divider for PGAs
6 _______________________________________________________________________________________
DIGITAL INPUTS
D1 D0
DIVIDER
RATIO
00 1
01 2
10 4
11 8
Table 1. Logic Control Truth Table
PIN
MAX5420 MAX5421
NAME FUNCTION
11V
DD Positive Supply Voltage
22V
SS Negative Supply Voltage
3 3 GND Ground
4, 5 4, 5 D0, D1 Digital Control Inputs. Drive D0 and D1 logic high or logic low to set the divider ratio.
See Logic Control Truth Table.
6 8 L Low Terminal of Resistor-Divider
7 9 W Resistor-Divider Output
8 10 H High Terminal of Resistor-Divider
— 6 MATCH_L Matching Resistor Low Terminal
— 7 MATCH_H Matching Resistor High Terminal
Pin Description
Switching Time and Layout Concerns
The switching time of the MAX5420/MAX5421 depends
on the capacitive loading at W. For best performance,
reduce parasitic board capacitance by minimizing the
circuit board trace from W to the op amp inverting input,
and choose an op amp with low input capacitance.
Chip Information
TRANSISTOR COUNT: 118
PROCESS: CMOS
MAX5420/MAX5421
Digitally Programmable Precision
Voltage Divider for PGAs
VOUT
+5V
MATCH_L
H
VDD
+5V
MATCH_H
L
VSS W
GND
MAX5421
VIN
MAX4493
H
W
LGND
+5V
+5V
MAX5420
VDD
VSS
VIN
MAX4237
VOUT
Figure 3. Programmable-Gain Amplifier with Op Amp Bias-
Current Matching
Figure 4. Programmable-Gain Amplifier
R1AR2AR3A
L
H
R3B R2B R1B
RATIO = 1
RATIO = 2
RATIO = 4
RATIO = 8
W
RATIO = R_B
R_A
1+
( )
Figure 1. Simplified Functional Diagram
R1AR2AR3A
L
H
R3B R2B R1B
RATIO = 1
RATIO = 2
RATIO = 4
RATIO = 8 W
RATIO = R_B
R_A
1+
( )
0.1µF
+5V
VDD
0.1µF
-5V
VSS
GND
PULSE
GENERATOR
D1 D0
MAX5421
TEKTRONIX P6245
OSCILLOSCOPE FET
PROBE
CL < 1pF
1MΩ
Figure 2. Switching Time Test Circuit
_______________________________________________________________________________________ 7
MAX5420/MAX5421
Digitally Programmable Precision
Voltage Divider for PGAs
8 _______________________________________________________________________________________
8LUMAXD.EPS
PACKAGE OUTLINE, 8L uMAX/uSOP
1
1
21-0036 J
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
MAX
0.043
0.006
0.014
0.120
0.120
0.198
0.026
0.007
0.037
0.0207 BSC
0.0256 BSC
A2 A1
c
eb
A
L
FRONT VIEW SIDE VIEW
E H
0.6±0.1
0.6±0.1
Ø0.50±0.1
1
TOP VIEW
D
8
A2 0.030
BOTTOM VIEW
16°
S
b
L
H
E
D
e
c
0°
0.010
0.116
0.116
0.188
0.016
0.005
8
4X S INCHES
-
A1
AMIN
0.002 0.950.75
0.5250 BSC
0.25 0.36
2.95 3.05
2.95 3.05
4.78
0.41
0.65 BSC
5.03
0.66
6°0°
0.13 0.18
MAX
MIN
MILLIMETERS
- 1.10
0.05 0.15
α
α
DIM
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
MAX5420/MAX5421
Digitally Programmable Precision
Voltage Divider for PGAs
10LUMAX.EPS
PACKAGE OUTLINE, 10L uMAX/uSOP
1
1
21-0061 REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
TOP VIEW
FRONT VIEW
1
0.498 REF
0.0196 REF
S6°
SIDE VIEW
α
BOTTOM VIEW
0° 0° 6°
0.037 REF
0.0078
MAX
0.006
0.043
0.118
0.120
0.199
0.0275
0.118
0.0106
0.120
0.0197 BSC
INCHES
1
10
L1
0.0035
0.007
e
c
b
0.187
0.0157
0.114
H
L
E2
DIM
0.116
0.114
0.116
0.002
D2
E1
A1
D1
MIN
-A
0.940 REF
0.500 BSC
0.090
0.177
4.75
2.89
0.40
0.200
0.270
5.05
0.70
3.00
MILLIMETERS
0.05
2.89
2.95
2.95
-
MIN
3.00
3.05
0.15
3.05
MAX
1.10
10
0.6±0.1
0.6±0.1
Ø0.50±0.1
H
4X S
e
D2
D1
b
A2 A
E2
E1 L
L1
c
α
GAGE PLANE
A2 0.030 0.037 0.75 0.95
A1
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
