ST EVAL-RHRICL1ATV1, EVAL-RHRICL1ALV1, EVAL-RHRICL1AFV1 User Manual

UM2605

User manual

EVAL-RHRICL1ATV1, EVAL-RHRICL1ALV1, EVAL-RHRICL1AFV1 evaluation

boards for the RHRPMICL1A

Introduction

This user manual provides an overview of the EVAL-RHRICL1ATV1, EVAL-RHRICL1ALV1 and EVAL-RHRICL1AFV1 evaluation
boards developed for the RHRPMICL1A, rad-hard integrated current limiter IC. One evaluation board for each of the three
operative modes of the RHRPMICL1A is available. Each evaluation tool includes all external components, needed for a
complete electrical evaluation of the device functionality in the selected configuration.

Table 1. Application tools

Type Part number Configuration Marking

Evaluation tools EVAL-RHRICL1ATV1 Re-triggerable RHRPMICL1ATV1 -RE-TRIGGERABLE

Evaluation tools EVAL-RHRICL1ALV1 Latched RHRPMICL1ALV1 - LATCHED ON/OFF

Evaluation tools EVAL-RHRICL1AFV1 Foldback RHRPMICL1AFV1 --FOLDBACK

Figure 1. EVAL-RHRICL1ATV1 (re-triggerable)

Figure 3. EVAL-RHRICL1AFV1 (foldback evaluation board)

Figure 2. EVAL-RHRICL1ALV1 (latched evaluation board)

UM2605 - Rev 1 - July 2019

For further information contact your local STMicroelectronics sales office.

www.st.com

1 Description

The RHRPMICL1A is an integrated current limiter designed to work as a high-side gate driver or intelligent power
switch driver, with an external P-channel power MOSFET. It can be used as a universal solution to protect a
power supply (from 8.5 V) from anomalous external current demand (for example, even in case of a short-circuit
condition).

The device can operate with a supply voltage range from 8.5 V to 52 V. An undervoltage lockout circuitry
guarantees the appropriate power supply integrity.

As the device can operate in floating ground configuration, in this user manual GND, the ground pin of the
RHRPMICL1A device (pin 7), and MGND the ground of main bus are defined.

In case of overload, the device behavior changes according to its configured mode of operation:

• Latched mode, the device provides current limitation capability for an external configurable time, called trip­off time, and if the overcurrent condition exceeds this time, the device switches OFF. In this case, the device
may be switched ON again through the telecommand pin only or a UVLO deactivation/activation cycle

• Re-triggerable mode, after the trip-off time, that is externally configurable, the device switches OFF and
remains in this state for a recovery time that is externally configurable. Once this time elapses, the device
recovers its typical operation mode if the overload condition disappears, otherwise it switches cyclically ON
and OFF again while the overload persists (hic-up mode)

• Foldback mode, in case of overload, the device provides current limitation with a value decreasing in
tracking with the output voltage, reaching a fixed and safe value even if a short-circuit persists

The mode of operation can be selected by configuring the RHRPMICL1A pins according to the following
configuration table, which is implemented in the evaluation boards:

UM2605

Description

Table 2. Applicable tools

Mode SET_FLB SET_STS TC_ON TC_OFF TON TOFF

Latched OFF 0 0 Telecommand Telecommand

Latched ON 0 1 Telecommand Telecommand

Re-triggerable 0 1 Vcc Vcc

Foldback 1 1 Vcc Vcc

1. GND refers to the RHRPMICL1A GND pin (pin 7), not to the main system ground (MGND).

C

C

C

GND

ON

ON

ON

(1)

GND

GND

C

OFF

GND

(1)

(1)

(1)

Status at

power-up

OFF

The characteristics and the main functionalities of each demonstration board are described in the following
sections.

ON

ON

ON

UM2605 - Rev 1

page 2/27

2 Common features and parameters

This section describes the features that are in common to the three boards, such as: UVLO, floating ground
configuration, current limitation, analog and digital telemetries, and explains how to customize them by changing
the external components on the board.

2.1 Undervoltage lockout and hysteresis settings

UM2605

Common features and parameters

The UVLO and hysteresis can be programmed by a set of three resistors: the R

A 220 kΩ resistor is generally used for RV, the other two resistors are obtained by the following equations:

Where K=150 is a corrective fixed value to be added to Eq. (1) in order to take into account that during the rising
phase of supply voltage, in the UVLO external resistor divider, R

the RHRPMICL1A.

2.2 Gate driving

The driver circuit is designed to drive an external P-channel power MOSFET (connected in high-side
configuration) providing on the Vg pin a voltage signal in the range VCC down to (VCC - 12 V). All the evaluation

boards are equipped with a through-hole socket where the power MOSFET can be easily housed.

When the device is ON and no current limitation is active, the Vg node is pulled down and the gate of the external
MOSFET is internally clamped, about 12 V below the supply voltage VCC. When the MOSFET has to be switched

OFF, Vg is brought up to VCC.

When the MOSFET is in current limitation mode, the Vg voltage is a value inside the range [VCC-12 V, VCC],
defined by the limitation control loop.

2.3

Current sense and limitation function

The voltage drop on the external R
compared with a fixed 100 mV internally generated threshold.

The current limitation threshold can be externally set according to the application requirements by a suitable
choice of the R

In the re-triggerable and latched evaluation boards it is:

If the voltage drop on R
internal timer starts counting the trip-off time TON and the device enters the current limitation mode. In such a
condition the limitation control loop is enabled in order to force Vg to the proper voltage level, limiting the current

to the load.

Please refer Section 5.1.2.2 Bill of material of the EVAL-RHRICL1AFV1 board for the current limitation settings
in the foldback mode evaluation board.

SENSE

resistor.

SENSE

, R

HYS

2.5*R

R

=

UVLO

R

UVLO

resistor is continuously monitored (by ISNS+ and ISNS- pins) and

SENSE

I

LIM

=

V

V

TH_OFF

= 100mV/R

TH_ON

2.5*R

V

− 2.5

V

− 2.5

− R

SENSE

− K

UVLO

is shorted by a non-ideal switch embedded in

HYS

UVLO

and RV.

exceeds 100 mV means that the current demand is becoming excessive: an

(1)

(2)

(3)

2.4 Floating ground configuration

The evaluation boards are equipped with the R
(GND) and the system ground (MGND).

An embedded 14.8 V Zener diode chain allows the device to operate in floating ground configuration and protects
the ICL device as its internal voltage supply is clamped at VZ ~ 15 V (14.8 V typ).

According to the voltage value of the Bus supply and depending on the value of RGND, the device can work (or
not) in floating ground condition, as follows:

UM2605 - Rev 1

floating resistance mounted between the GND pin of the ICL

GND

page 3/27

UM2605

Analog telemetry

1. Vcc <14.8 V

The Zener diode chain is OFF and the R
the device. Since the typical current consumption of the ICL device is ~ 1.5 mA (the current contribution of the

Zener diode chain is null in this case), in order to have a certain V

1. Vcc > 14.8 V

In this case the Zener diode chain is enabled and the R
consumption of the device, flowing through R

This current consumption is given by the sum of two contributors:

1. The net current consumption of the RHRPMICL1A (considering the internal Zener diode chain current as
zero)

2. The current consumption of the Zener diode chain in ON-state

For example, if we want to set the maximum current consumption of the RHRPMICL1A device to 2 mA, the value
of R

GND

is:

The RHRPMICL1A can be configured to work also with power Buses with voltage higher than 52 V, by adding the
proper protection components to the application.

Guidelines on this feature are provided in the RHRPMICL1A datasheet.

is used to protect the system against a potential internal failure of

GND

, the R

GND

V

R

GND

resistor from GND pin to the system ground MGND.

GND

R

GND

GND

=

1.5mA

GND

VCC− 14.8V

=

2mA

is also used to limite the maximum current

GND

value is:

(4)

(5)

2.5 Analog telemetry

The analog telemetry circuit gives information about the current flowing across the load. This circuit provides on
the TM pin a source current whose value is instantly proportional to the current flowing from the bus supply line to
the load. The voltage drop (VTM) on the external resistor RTM connected between the TM pin and MGND, is

proportional to the load current (I

) flowing through R

SENSE

RTM=

V

I

RTM

2.6 Digital telemetry (status telemetry)

The status telemetry circuit gives some information about the device status, which can be retrieved by monitoring
the STS output pin, according to the following table.

Table 3. Signal on digital telemetry pin

STS pin signal RHRPMICL1A driver status

HIGH ON

LOW OFF

The STS is an open drain pin that can source a 100 μA fixed current; it is typically connected to MGND through
an external resistor R

The following picture shows the telemetry signals during the ICL operation.

, setting the desired high logic level value V

STS

TM

=

V

TM

I

SENSE

, thus performing a current/voltage conversion:

SENSE

R

TMS

*

R

SENSE

as follows:

H_STS

(6)

UM2605 - Rev 1

page 4/27

Figure 4. Telemetry signals

UM2605

Digital telemetry (status telemetry)

UM2605 - Rev 1

page 5/27

CVcc_2_btm

4.7 uF

SCH2

STPS3150

Csts_2

4.7 pF

Ctm_2 4.7 pF

Csns_2 1uF

Rcomp_2

1k

C6

4.7uF

C8

4.7uF

ZD2

1SMB5929BT3G

U2

1

2345678

9

10

11

1718192016

15

14

13

12

VD_2

VCC+_2

P-ch2

STRH40P10

0

C5

4.7uF

Rhys_2

1.5k

Ruvlo_2

13k

Rv_2

220k

Rsns1_2

40m

VCC+_2

1
2

1
2

C7

4.7uF

0

Rsns2_2

40m

Rir_2

100k

RGND_2

16.2k

Con_2

27nF

I_STM- _1

I_STM+_1

Rtms+_2

5k

Rtms-_2

5k

ISNS

-_1

ISNS+_1

VCC+_2

VCC-_2

VCC-_2

Ccomp_2

2.2 nF

COMP_2

VD_2

CVcc_2

100nF

RETRIGGERABLE MODE

VCC+_2

SET_FLB

SET_STS

I_REF

T_ON

T_OFF

STS

ICL_GND

Rsts_2

50k

Rtm_2 100k

TM

0

HYS

UVLO

UVLO

HYS

VCC

Rg_2

4R7

Coff_2

470nF

TC_OFF

TC_ON

CN3

CN4

VG

CFLAT20

Features: EVAL-RHRICL1ATV1, re-triggerable mode

3 Features: EVAL-RHRICL1ATV1, re-triggerable mode

3.1 Getting started

The EVAL-RHRICL1ATV1 evaluation board is customized to allow the test of re-triggerable operative mode of the
RHRPMICL1A integrated current limiter (ICL).

In the re-triggerable mode, the ICL restarts automatically, recovering its normal operating mode if the current
limitation cause is removed; besides, during any overload or output short-condition events, after the T

recovery time elapses, the device tries to re-start for a dedicated TON slot time (trip-off time).

The configuration pins of the ICL in this mode are:

• Telecommand interface: disabled (TC_ON and TC_OFF both connected to VCC)

• SET_STS is connected to V

• SET_FLB is connected to GND

• TON is connected to C

• TON is connected to C

The external components of the board are pre-set to accomplish the following features:

• VCC = 50 V with V

TH_ON

• HYS = 4 V

• I

LIM

= 5 A

• TON ˜ 3 ms (typ 2.7 ms) with T

The evaluation board schematic is shown below. Please note that the capacitor Csns_2, connected in parallel to
the R

, affects the dynamic of the reaction time and therefore the decision whether to mount it or not is up to

SENSE

the application needs of the end user.

CC

ON

OFF

= 44 V and V

OFF

= 40 V

TH_OFF

˜ 1s (typ. 0.94 s)

UM2605

OFF

Figure 5. Re-triggerable evaluation board (schematic)

UM2605 - Rev 1

page 6/27

3.2 Operations

3.2.1 Power-on and testing environment

Connect a 50 V power supply to CN3, the load on CN4. The telecommand section is not activated in this
evaluation board. The analog and digital telemetries are accessible on the RTM and R

Figure 6. Testing environment

resistors respectively.

STS

UM2605

Operations

3.2.2 Trip-on and trip-off time programming

In re-triggerable mode, if the duration of the overcurrent is greater than the trip-off time TON, the external
MOSFET is switched OFF after the TON time has elapsed and stays OFF for the recovery time T
T

time elapses, the device restarts autonomously to its normal condition, turning on again the MOSFET, if the

OFF

current limitation cause is removed. Otherwise it switches cyclically on and off again while the overload persists
(hic-up mode).

The trip-off time TON is set by the CON capacitor connected between the pins TON and GND, and it is calculated
by the following equation:

In the same way, the recovery time T
T

and GND. The C

OFF

capacitor is charged with a constant current whose value is a fraction (typ. 1/20) of I

OFF

current (externally set by the resistor RIR connected between the I_REF pin and GND). The charging phase of
C

capacitor starts as soon as the TON time has elapsed, therefore the T

OFF

time defined by:

In the equations above, unit for TON and T

The typical behavior of the device configured in re-triggerable mode is depicted below (timing is not in scale).

is set through the external capacitor C

OFF

OFF

. When the

OFF

TON= RIR*C

T

= 20*RIR*C

OFF

ON

OFF

connected between the pins

OFF

time is equal to the C

OFF

OFF

charging

are in seconds, for resistance in Ω and for capacitance in Farads.

(7)

REF

(8)

UM2605 - Rev 1

page 7/27

UM2605

Operations

Figure 7. Overload shorter than TON+T

Figure 9. Continuous short-circuit

OFF

Figure 8. Overload longer than TON+T

OFF

UM2605 - Rev 1

page 8/27

3.3.1 Layout of the EVAL-RHRICL1ATV1 board

UM2605

Operations

Figure 10. EVAL-RHRICL1ATV1 top layout

Figure 11. EVAL-RHRICL1ATV1 bottom layout

UM2605 - Rev 1

page 9/27