Datasheet MAX4172 (Maxim) - 5
| Manufacturer | Maxim |
| Description | Low-Cost, Precision, High-Side Current-Sense Amplifier |
| Pages / Page | 9 / 5 — Typical Operating Characteristics (continued). STARTUP DELAY. V+ to PG … |
| Revision | 4 |
| File Format / Size | PDF / 1.6 Mb |
| Document Language | English |
Typical Operating Characteristics (continued). STARTUP DELAY. V+ to PG POWER-UP DELAY. Pin Description. PIN. NAME. FUNCTION
Model Line for this Datasheet
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link to page 6 link to page 6 MAX4172 Low-Cost, Precision, High-Side Current-Sense Amplifier
Typical Operating Characteristics (continued)
(V+ = +12V, VRS+ = 12V, ROUT = 1kΩ, TA = +25°C, unless otherwise noted.)
STARTUP DELAY V+ to PG POWER-UP DELAY
MAX4172-10 MAX4172-11 VOUT PG 500mV/div 2V/div GND GND V+ V+ 2V/div 2V/div GND GND 5µs/div 10ms/div VSENSE = 100mV 100kW PULLUP 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
(RSENSE), from the RS+ node to the RSnode. Current The MAX4172 is a unidirectional, high-side current- flows through RG1 and Q1, and into the current mirror, sense amplifier with an input common-mode range that is where it is multiplied by a factor of 50 before appearing independent of supply voltage. This feature not only at OUT. allows the monitoring of current flow into a battery in deep To analyze the circuit of Figure 1, assume that current discharge, but also enables high-side current sensing at flows from RS+ to RS-, and that OUT is connected to voltages far in excess of the supply voltage (V+). GND through a resistor. Since A1’s inverting input is high The MAX4172 current-sense amplifier’s unique topology impedance, no current flows though RG2 (neglecting the simplifies current monitoring and control. The MAX4172’s input bias current), so A1’s negative input is equal to amplifier operates as shown in Figure 1. The battery/ VSOURCE - (ILOAD x RSENSE). A1’s open-loop gain forces load current flows through the external sense resistor its positive input to essentially the same voltage level as the negative input. Therefore, the drop across RG1 equals www.maximintegrated.com Maxim Integrated │ 5
Typical Operating Characteristics (continued)
(V+ = +12V, VRS+ = 12V, ROUT = 1kΩ, TA = +25°C, unless otherwise noted.)
STARTUP DELAY V+ to PG POWER-UP DELAY
MAX4172-10 MAX4172-11 VOUT PG 500mV/div 2V/div GND GND V+ V+ 2V/div 2V/div GND GND 5µs/div 10ms/div VSENSE = 100mV 100kW PULLUP 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
(RSENSE), from the RS+ node to the RSnode. Current The MAX4172 is a unidirectional, high-side current- flows through RG1 and Q1, and into the current mirror, sense amplifier with an input common-mode range that is where it is multiplied by a factor of 50 before appearing independent of supply voltage. This feature not only at OUT. allows the monitoring of current flow into a battery in deep To analyze the circuit of Figure 1, assume that current discharge, but also enables high-side current sensing at flows from RS+ to RS-, and that OUT is connected to voltages far in excess of the supply voltage (V+). GND through a resistor. Since A1’s inverting input is high The MAX4172 current-sense amplifier’s unique topology impedance, no current flows though RG2 (neglecting the simplifies current monitoring and control. The MAX4172’s input bias current), so A1’s negative input is equal to amplifier operates as shown in Figure 1. The battery/ VSOURCE - (ILOAD x RSENSE). A1’s open-loop gain forces load current flows through the external sense resistor its positive input to essentially the same voltage level as the negative input. Therefore, the drop across RG1 equals www.maximintegrated.com Maxim Integrated │ 5
