MAX931CUA+ Maxim Integrated Products, MAX931CUA+ Datasheet - Page 10

• Manufacturer Part Number: MAX931CUA+
• Description: IC COMPARATOR W/REF 8-UMAX
• Manufacturer: Maxim Integrated Products
• Type: with Voltage Referencer

Specifications of MAX931CUA+

• Number Of Elements: 1
• Output Type: CMOS, TTL
• Voltage - Supply: 2.5 V ~ 11 V, ±1.25 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
• Number Of Channels: 1 Channel
• Product: Analog Comparators
• Offset Voltage (max): +/- 10 mV
• Supply Voltage (max): 11 V
• Supply Voltage (min): 2.5 V
• Supply Current (max): 3.2 uA
• Maximum Power Dissipation: 330 mW
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: 0 C
• Comparator Type: General Purpose
• No. Of Comparators: 1
• Response Time: 12µs
• Ic Output Type: CMOS, TTL
• Supply Current: 2.5µA
• Supply Voltage Range: ± 1.25V To ± 5.5V
• Amplifier Case Style: µMAX
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

maximum difference between REF and HYST (50mV)
will therefore produce a 100mV max hysteresis band.
Use the following equations to determine R1 and R2:
Where I
should not exceed the REF source capability, and
should be significantly larger than the HYST input
current. I
usually appropriate. If 2.4MΩ is chosen for
R2 (I
approximated as:
When hysteresis is obtained in this manner for
the MAX932/MAX933, the same hysteresis applies to
both comparators.
Hysteresis can be set with two resistors using positive
feedback, as shown in Figure 4. This circuit generally
draws more current than the circuits using the HYST
pin on the MAX931/MAX932/MAX933, and the high
feedback impedance slows hysteresis. The design
procedure is as follows:
1. Choose R3. The leakage current of IN+ is under 1nA
Ultra Low-Power, Low-Cost
Comparators with 2% Reference
Figure 3. Programming the HYST Pin
10
(up to +85°C), so the current through R3 can be
around 100nA and still maintain good accuracy.
The current through R3 at the trip point is V
or 100nA for R3 = 11.8MΩ. 10MΩ is a good
practical value.
REF
______________________________________________________________________________________
R1 (k ) = V
R1 =
R2 =
REF
= 0.5µA), the equation for R1 and V
REF
(the current sourced by the reference)
2
1.182 –
values between 0.1µA and 4µA are
R2
R1
V
HB
HB
I
I
REF
I
REF
REF
(mV)
V
HB
6
5
2
REF
HYST
2.5V TO 11V
MAX931
MAX932
MAX933
V+
V-
Hysteresis (MAX934)
7
2
HB
REF
can be
/R3,
2. Choose the hysteresis voltage (V
3. Calculate R1.
4. Choose the threshold voltage for V
5. Calculate R2.
6. Verify the threshold voltages with these formulas:
Figure 4. External Hysteresis
between the upper and lower thresholds. In this
example, choose V
this example, choose V
A 1% preferred value is 64.9kΩ.
R2 =
V
IN
R1 = R3
V rising :
V
V falling :
V
IN
IN
THR
THF
65.44k
10M
100k
R1
(V
(1.182
REF
V
V
V
R2
THR
REF
THR
V
V
0.05
3
HB
R1)
5
HB
100k)
1
V
REF
R1
= 50mV.
THR
R1
1
R1
MAX934
1
R3
= 3V.
GND
100k
R1
V
1
R3
1
1
V+
V+
V-
IN
HB
10M
rising (V
R2
OUT
1
R3
1
), the voltage
R3
THR
1
). In