ISL88042IRTHFZ-TK 데이터 시트보기 (PDF) - Renesas Electronics

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ISL88042IRTHFZ-TK

Quadruple Voltage Monitor

Renesas Electronics 

ISL88042

Electrical Specifications Over the recommended operating conditions, unless otherwise specified. (Continued)

SYMBOL

PARAMETER

TEST CONDITIONS

MIN

MAX

(Note 5) TYP (Note 5) UNITS

MANUAL RESET

VMRL MR Input Voltage Low

0.8

V

VMRH MR Input Voltage High

VDD - 0.6

V

tMR

MR Minimum Pulse Width

550

ns

RPU

Internal Pull-Up Resistor

10

k

NOTE:

5. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization

and are not production tested.

Pin Descriptions

RST

The RST output is an open drain output, which is asserted

low whenever the following occurs:

1. The device is initially powered up to 1V or

2. VDD, V2MON, V3MON or V4MON fall below their

minimum voltage sense level.

MR

The MR input is an active low debounced input to which a

user can connect a push-button to add manual reset

capability or use a signal to pull low. MR has an internal

pull-up resistor.

VDD

The VDD pin is the IC power supply terminal. The voltage at

this pin is compared against an internal factory-programmed

voltage trip point, VTH1. RST is first asserted low when the

device is initially powered and VDD < 1V and then at any

time thereafter when VDD falls below VTH1. The device is

designed with hysteresis to help prevent chattering due to

noise and is immune to brief power-supply transients.

V2MON

The V2MON input is the second preset monitored voltage

that causes the RST output to go low when the voltage on

V2MON falls below VTH2.

V3MON, and V4MON

The VxMON inputs provide monitoring and UV compliance

of three additional voltages through resistor dividers. A reset

is issued on the ISL88042 if the voltage on any VxMON falls

below the internal VREF of 0.6V.

.

VDD

V2MON

V3MON

V4MON

RST

ISL88042

MR

PB

RESET

SIGNAL

GND

FIGURE 1. TYPICAL APPLICATION DIAGRAM

Principles of Operation

The ISL88042 device provides those functions needed for

monitoring critical voltages, such as power-supply and battery

functions in microprocessor systems. It provides such features

as Power-On Reset control, supply voltage supervision, and

Manual Reset Assertion. The integration of all these features

along with competitive reset threshold accuracy and low power

consumption, makes the ISL88042 device suitable for a wide

variety of applications needing multi-voltage monitoring. See

Figure 1 for the “Typical Application Diagram”.

Low Voltage Monitoring

During normal operation, the ISL88042 monitors the voltage

levels of VDD, V2MON, V3MON and V4MON. If the voltage on

any of these four inputs falls below their respective voltage trip

points, a reset is asserted (RST = low) to prevent the

microprocessor from operating during a power failure or

brownout condition. This reset signal remains low until the

voltages exceeds the voltage threshold settings for the reset

time delay period tPOR.

The ISL88042 allows users to customize the minimum voltage

sense level for two of the four monitored voltages. For example,

the user can adjust the voltage input trip point (VTRIP) for the

V3MON and V4MON inputs. To do this, connect an external

resistor divider network to the VxMON pin in order to set the trip

FN6655 Rev 2.00

July 26, 2010

Page 4 of 8

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