Datasheet
MAX4036–MAX4039
Low I
BIAS
, +1.4V/800nA, Rail-to-Rail Op Amps
with +1.2V Buffered Reference
12 ______________________________________________________________________________________
3) Calculate R1:
4) Choose the threshold voltage for V
IN
rising (V
THR
).
In this example, choose V
THR
= 2.0V.
5) Calculate R2:
6) Verify the threshold voltages with these formulas:
V
IN
rising:
V
IN
falling:
In this application, the MAX4036–MAX4039 supply cur-
rent will vary, depending on the output state of the
comparator.
Power Supplies and Layout
The MAX4036–MAX4039 operate from a single 1.4V
(MAX4036/MAX4038) or 1.8V (MAX4037/MAX4039) to
3.6V power supply. Bypass V
DD
with a 0.1µF capacitor
to ground to minimize noise.
Good layout techniques optimize performance by
decreasing the amount of stray capacitance to the op
amp’s inputs and outputs. To decrease stray capaci-
tance, minimize trace lengths by placing external com-
ponents close to the device.
The exposed paddle (EP) on the TDFN packages of the
MAX4038 and MAX4039 is internally connected to the
device substrate, V
SS
. Connect the exposed paddle to
V
SS
or leave EP unconnected. Running traces below the
exposed paddle is not recommended.
Chip Information
MAX4036 TRANSISTOR COUNT: 49
MAX4037 TRANSISTOR COUNT: 119
MAX4038 TRANSISTOR COUNT: 146
MAX4039 TRANSISTOR COUNT: 146
PROCESS: BiCMOS
VV
RV
R
THF THR
DD
=−
×
⎛
⎝
⎜
⎞
⎠
⎟
1
3
VVR
RR R
THR REF
=××++
⎛
⎝
⎜
⎞
⎠
⎟
1
1
1
1
2
1
3
R
V
VRRR
V
Vk k M
k
THR
REF
2
1
1
1
1
1
3
1
20
1 2 210
1
210
1
10
325
.
.
=
×
⎛
⎝
⎜
⎞
⎠
⎟
−−
⎡
⎣
⎢
⎢
⎤
⎦
⎥
⎥
=
×
⎛
⎝
⎜
⎞
⎠
⎟
−−
⎡
⎣
⎢
⎤
⎦
⎥
=
ΩΩΩ
Ω
RR
V
V
M
V
V
k
HB
DD
13
10
05
24
210
.
.
=×
=×
=
Ω
Ω
V
REF
R3
R1
R2
V
BATT
V
BGOOD
V
SS
V
SS
V
DD
V
DD
IN+
REF
IN-
OUT
MAX4037
Figure 4. Battery Monitoring
Selector Guide
PART NO. OF AMPLIFIERS REFERENCE
MAX4036 1 —
MAX4037 1 √
MAX4038 2 —
MAX4039 2 √
Ordering Information (continued)
PART TEMP RANGE
PIN-
PACKAGE
TOP
MARK
MAX4039EBL-T -40°C to +85°C 9 UCSP AEH
MAX4039ETB-T -40°C to +85°C 10 TDFN-EP* AAN
MAX4039EUB -40°C to +85°C 10 µMAX —
-
Denotes a package containing lead.
*
EP = Exposed pad.