MAX6788 Просмотр технического описания (PDF) - Maxim Integrated

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MAX6788

Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages

Maxim Integrated 

Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level

Battery Monitors in Small TDFN and TQFN Packages

Monitoring a Battery Voltage Higher

than the Allowable VBATT

For monitoring higher voltages, supply a voltage to BATT,

which is within the specified supply range, and power the

input resistive divider from the high voltage to be moni-

tored. Do not exceed the Absolute Maximum Ratings.

Maintaining Reference Accuracy

Since the ground connection of the MAX6782–MAX6790

has a small series resistance, any current flowing into an

output flows to ground and causes a small voltage to

develop from the internal ground to GND. This has the

effect of slightly increasing the reference voltage. To mini-

mize the effect on the reference voltage, keep the total

output sink current below 3mA.

R1

BATT

IN_

LBO_

R2

MAX6782

REF MAX6783

MAX6784

MAX6785

HADJ_

GND

Adding External Capacitance to Reduce

Noise and Transients

If monitoring voltages in a noisy environment, add a

bypass capacitor of 0.1µF from BATT to GND as close

as possible to the device. For systems with large tran-

sients, additional capacitance may be required.

Reverse-Battery Protection

To prevent damage to the device during a reverse-battery

condition, connect the MAX6782–MAX6785 in the configu-

ration shown in Figure 6a or 6b. For the internal reverse-

battery protection to function correctly on the MAX6782–

MAX6790, several conditions must be satisfied:

• The connections to IN_/LBL_/LBH_ must be made to

the center node of a resistive divider going from

BATT to GND. The Thevenin equivalent impedance

of the resistive divider must not fall below 1kΩ in

order to limit the current.

• HADJ_ (MAX6782–MAX6785 only) must either be

connected to GND or to the center node of a resis-

tive divider going from REF to GND.

• The outputs may only be connected to devices pow-

ered by the same battery as the MAX6782–

MAX6790.

Note that the MAX6782–MAX6790 will not protect other

devices in the circuit.

Additional Application Circuit

Figure 7 shows the MAX6786/MAX6787/MAX6788 in a

typical two-battery-level monitoring circuit.

A) FACTORY PRESET HYSTERESIS CONNECTION

R1

R2

R3

R4

1

BATT

IN_

LBO_

REF

HADJ_

MAX6782

MAX6783

MAX6784

MAX6785

GND

BATT

LBL1

LBO1

LBH1

MAX6786

MAX6787

MAX6788

LBL2

LBO2

LBH2

GND

B) EXTERNAL HYSTERESIS ADJUST CONNECTION

Figure 6. Internal Preset or Externally Adjusted Hysteresis

Connection

Figure 7. Two-Battery-Level Monitor Configuration

14 ______________________________________________________________________________________

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