MAX4172(1996) 데이터 시트보기 (PDF) - Maxim Integrated

부품명

상세내역

제조사

MAX4172
(Rev.:1996)

Low-Cost, Precision, High-Side Current-Sense Amplifier

Maxim Integrated 

Low-Cost, Precision, High-Side

Current-Sense Amplifier

____________________________Typical Operating Characteristics (continued)

(V+ = +12V, VRS+ = 12V, ROUT = 1kΩ, TA = +25°C, unless otherwise noted.)

START-UP DELAY

MAX4172-10

V+ to PG POWER-UP DELAY

MAX4172-11

VOUT

500mV/div

GND

PG

2V/div

GND

V+

2V/div

GND

VSENSE = 100mV

5µs/div

V+

2V/div

GND

10µs/div

100kΩ PULL-UP RESISTOR FROM PG TO +4V

______________________________________________________________Pin Description

PIN

NAME

FUNCTION

1

RS+

Power connection to the external sense resistor. The “+” indicates the direction of current flow.

2

RS-

Load-side connection for the external sense resistor. The “-” indicates the direction of current flow.

3, 4

N.C.

No Connect. No internal connection. Leave open or connect to GND.

5

GND

Ground

6

OUT

Current Output. OUT is proportional to the magnitude of the sense voltage (VRS+ - VRS-). A 1kΩ

resistor from OUT to ground will result in a voltage equal to 10V/V of sense voltage.

7

PG

Power Good Open-Collector Logic Output. A low level indicates that V+ is sufficient to power the

MAX4172, and adequate time has passed for power-on transients to settle out.

8

V+

Supply Voltage Input for the MAX4172

_______________Detailed Description

The MAX4172 is a unidirectional, high-side current-sense

amplifier with an input common-mode range that is inde-

pendent of supply voltage. This feature not only allows

the monitoring of current flow into a battery in deep dis-

charge, but also enables high-side current sensing at

voltages far in excess of the supply voltage (V+).

The MAX4172 current-sense amplifier’s unique topolo-

gy simplifies current monitoring and control. The

MAX4172’s amplifier operates as shown in Figure 1.

The battery/load current flows through the external

sense resistor (RSENSE), from the RS+ node to the RS-

node. Current flows through RG1 and Q1, and into the

current mirror, where it is multiplied by a factor of 50

before appearing at OUT.

To analyze the circuit of Figure 1, assume that current

flows from RS+ to RS-, and that OUT is connected to

GND through a resistor. Since A1’s inverting input is

high impedance, no current flows though RG2 (neglect-

ing the input bias current), so A1’s negative input is

equal to VSOURCE - (ILOAD x RSENSE). A1’s open-loop

gain forces its positive input to essentially the same

voltage level as the negative input. Therefore, the drop

across RG1 equals ILOAD x RSENSE. Then, since IRG1

_______________________________________________________________________________________ 5

Share Link: