ROHM BD37A41FVM, BD87A28FVM, BD87A29FVM, BD87A34FVM, BD87A41FVM Technical data

TECHNICAL NOTE

Power Management LSI Series for Automotive Body Control

Voltage Detector ICs
with Watchdog Timer

BD37A19FVM，BD37A41FVM，BD87A28FVM，BD87A29FVM
BD87A34FVM，BD87A41FVM，BD99A41F

zDescription

The BD37A19FVM,BD37A41FVM,BD87A28FVM,BD87A29FVM,BD87A34FVM,BD87A41FVM,BD99A41F is a watchdog timer reset IC. It

delivers a high precision detection voltage of ±1.5% and a super-low current consumption of 5 µA (Typ.). It can be used in a wide range of

electronic devices to monitor power supply voltages and in system operation to prevent runaway operation.

zFeatures

1) High precision detection voltage: ±1.5%, ±2.5% (Ta = −40°C to 105°C)

2) Super-low current consumption: 5 µA (Typ.)

3) Built-in watchdog timer

4) Reset delay time can be set with the CT pin's external capacitance.

5) Watchdog timer monitor time and reset time can be set with the CTW pin's external capacitance.

6) Output circuit type: N-channel open drain

7) Package: MSOP8(BD37A□□FVM,BD87A□□FVM)／SOP8(BD99A41F)

zApplications

All devices using microcontrollers or DSP, including vehicle equipment, displays, servers, DVD players, and telephone systems.

zProduct line

INH logic H: Active L: Active

Model BD37A□□FVM BD99A41F BD87A□□FVM

Detection voltage 1.9 V/4.1V 4.1 V 2.8V/2.9V/3.4 V/4.1V

●Absolute maximum ratings (Ta = 25°C)

Parameter Symbol Limit Unit

Power supply voltage VDD −0.3 to 10 V

CT pin voltage VCT −0.3 to VDD + 0.3 V

CTW pin voltage VCTW −0.3 to VDD + 0.3 V

RESET pin voltage VRESET −0.3 to VDD + 0.3 V

INH pin voltage VINH −0.3 to VDD + 0.3 V

CLK pin voltage VCLK −0.3 to VDD + 0.3 V

Power dissipation Pd

Operating ambient temperature Topr −40 to + 105 °C

Storage temperature Tstg −55 to + 125 °C

Maximum junction temperature Tjmax 125 °C

*1 MSOP8 : Reduced by 4.70 mW/°C over 25°C, when mounted on a glass epoxy board (70 mm × 70 mm × 1.6 mm).

*2 SOP8 : Reduced by 5.50 mW/°C over 25°C, when mounted on a glass epoxy board (70 mm × 70 mm × 1.6 mm).

470*1

550*2

mW

Ver.B July 2006

●Recommended operating ranges (Ta = −40°C to 105°C)

Parameter Symbol Min. Max. Unit

RESET power supply voltage VDD RESET 1.0 10 V

WDT power supply voltage VDD WDT 2.5 10 V

●Electrical characteristics (Unless otherwise specified, Ta = −40°C to 105°C, VDD = 5 V)

Parameter Symbol

Min. Typ. Max.

Limit

Unit Conditions

[Overall]

Total supply current 1

(during WDT operation)

Total supply current 2

(when WDT stopped)

IDD1 — 5 14 µA

IDD2 — 5 14 µA INH : WDT OFF Logic Input

INH : WDT ON Logic Input

CTW = 0.1 µF

Output leak current Ileak — — 1 µA VDD = VDS = 10 V

Output current capacity IOL 0.7 — — mA VDD = 1.2 V, VDS = 0.5 V

[RESET]

1.9V Detect VDET1 1.871 1.900 1.929 V Ta = 25°C

Detection

voltage 1

2.8V Detect VDET1 2.758 2.800 2.842 V Ta = 25°C

2.9V Detect VDET1 2.886 2.930 2.974 V Ta = 25°C

3.4V Detect VDET1 3.349 3.400 3.451 V Ta = 25°C

4.1V Detect VDET1 4.039 4.100 4.162 V Ta = 25°C

1.9V Detect VDET2 1.852 1.900 1.948 V Ta = −40 to 105°C

Detection

voltage 2

2.8V Detect VDET2 2.730 2.800 2.870 V Ta = −40 to 105°C

2.9V Detect VDET2 2.857 2.930 3.003 V Ta = −40 to 105°C

3.4V Detect VDET2 3.315 3.400 3.485 V Ta = −40 to 105°C

4.1V Detect VDET2 4.007 4.100 4.202 V Ta = −40 to 105°C

1.9V Detect Vrhys VDET × 0.03 VDET × 0.13 VDET × 0.19 V Ta = −40 to 105°C

Hysteresis

width

2.8V Detect Vrhys VDET × 0.018 VDET × 0.045 VDET × 0.060 V Ta = −40 to 105°C

2.9V Detect Vrhys VDET × 0.02 VDET × 0.05 VDET × 0.06 V Ta = −40 to 105°C

3.4V Detect Vrhys VDET × 0.02 VDET × 0.05 VDET × 0.07 V Ta = −40 to 105°C

4.1V Detect Vrhys VDET × 0.018 VDET × 0.035 VDET × 0.050 V Ta = −40 to 105°C

RESET transmission delay

time: low → high

TPLH 3.9 6.9 10.1 ms

CT = 0.001 µF

When VDD = VDET ±0.5 V

*1

Delay circuit resistance Rrst 5.8 10.0 14.5 MΩ VCT = GND

Delay pin threshold voltage VCTH VDD × 0.3 VDD × 0.45 VDD × 0.6 V RL = 470 KΩ

Delay pin output current ICT 150 — — µA VDD = 1.50 V, VCT = 0.5 V

Min. operating voltage VOPL 1.0 — — V VOL ≤ 0.4 V, RL = 470 KΩ

[WDT]

WDT monitor time TwH 7.0 10.0 20.0 ms CTW = 0.01 µF*2

WDT reset time TwL 2.4 3.3 7.0 ms CTW = 0.01 µF*3

Clock input pulse width TWCLK 500 — — ns

CLK high threshold voltage VCLKH VDD × 0.8 — VDD V

CLK low threshold voltage VCLKL 0 — VDD × 0.3 V

CLK high threshold voltage VINHH VDD × 0.8 — VDD V

CLK low threshold voltage VINHL 0 — VDD × 0.3 V

CTW charge current ICTWC 0.25 0.50 0.75 µA VCTW = 0.2 V

CTW discharge current ICTWO 0.75 1.50 2.00 µA VCTW = 0.8 V

*1 TPLH can be varied by changing the CT capacitance value.

TPLH (s) ≈ 0.69 × Rrst (MΩ) × CT (µF) Rrst = 10 MΩ (Typ.)

*2 TwH can be varied by changing the CT capacitance value.

TwH (s) ≈ (0.5 × CTW (µF))/ICTWC (µA) ICTWC = 0.5 µA (Typ.)

*3 TwL can be varied by changing the CTW capacitance value.

TwL (s) ≈ (0.5 × CTW (µF))/ICTWO (µA) ICTWO = 1.5 µA (Typ.)

Note: This IC is not designed to be radiation-resistant.

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●Reference data (Unless otherwise specified, Ta = 25°C) : 4.1V Detection

リセット

時間

監視時間

リセット

時間

12

10

8

6

4

2

OUTPUT VOLTAGE: VOUT [V]

0

0246810

SUPPLY VOLTAGE: VDD [V]

Fig. 1 Detection Voltage

2

1.5

1

0.5

0

-0.5

CTW PIN CURRENT: ICTW [µA]

-1
012345

CTW PI N VOLTAGE: VC TW [V]

Fig. 4 CTW Charge Discharge Current

10

8

6

4

2

CIRCUIT CURRENT: IDD [µA]

0

0246810

SUPPLY VOLTAGE: VD D [ V]

Fig. 2 Total Supply Current

2

1.5

1

0.5

RESET CURRENT: IRESET [mA]

0

02 46 810

RESET VOLTAGE: VRESET [V]

Fig. 5 Output Current

Ta=105°C

Ta= −40°C

10000

1000

100

Monitor time

10

Reset time

1

WDT RESET TIME: Tw [ms]

0.1

0.001 0.01 0.1 1 10

CTW PIN CAPACITY : CTW[µF]

CT PIN VOLTAGE: VCT [V]

Fig. 7 WDT Time vs Capacitance

13

12

11

10

9

OUTPUT DELAY RESISTANCE: Rrst [MΩ]

8

-40 0 40 80

AMBIENT TEMPERATURE: Ta [℃]

Fig. 10 CT Pin Circuit Resistance vs

Temperature

5

4.75

4.5

4.25

4

3.75

DETECTION VOLTAGE: VDET [V]

3.5

-40 0 40 80

AMBIENT TEMPER ATURE: Ta [℃]

Fig. 8 Detection Voltage vs Temperature

10

9

8

7

6

OUTPUT DELAY TIME: TPLH [ms]

5

-40 0 40 80

AMBIENT TEMPERATURE: Ta [℃]

Fig. 11 RESET Transmission Delay

Time vs Temperature

Ta= 2 5° C

Ta= −40°C

Ta=105°C

L→H

H→L

Ta= 2 5° C

1400

1200

1000

800

600

400

200

CT PIN CURRENT: ICT [µA]

0

012345

CT PIN VOLTAGE: VCT [V]

Fig. 3 Delay Pin Current vs

10000

1000

100

10

OUTPUT DELAY TIME: TPLH [ms]

1

0.0001 0.001 0.01 0.1

Fig. 6 RESET Transmission Delay

1

0.75

0.5

0.25

OPERATING VOLTAGE: VOPL [V]

0

-40 0 40 80

AMBIENT TEMPER ATURE: Ta [℃]

Fig. 9 Operating Marginal Voltage vs

15

12

9

6

3

WDT RESET TIME: Tw [ms]

0

-40 0 40 80

AMBIENT TEMPER ATURE: Ta [℃]

Fig. 12 WDT Time vs Temperature

Power Supply Voltage

CT PIN CAPACITY: CT [µF]

Time vs Capacitance

Temperature

Monitor time

Reset time

3/8