JAJSNN2 データシート

JAJSNN2B October 2023 – July 2024 UCC25660

PRODUCTION DATA

8.2.2.20 Burst Mode Programming

The LL pin voltage (VLLB) and the resistor divider that connected to the LL pin allow the designer to set the HFBurstEntry and LFBurstEntry thresholds as shown below.

Equation 73.

V L L B = \frac{R_{L L_l o w e r} \cdot V 5 P}{R_{L L_u p p e r} + R_{L L_l o w e r}}

Equation 74.

V L L A = V L L B + \frac{R_{L L_l o w e r} R_{L L_u p p e r}}{R_{L L_u p p e r} + R_{L L_l o w e r}} \cdot I_{L L P r g m}

As shown in Table 7-2, (VLLA-VLLB) voltage determines the VLLB/HFBurstEntry ratio.

For this design, (VLLB/HFBurstEntry) = 0.55 is considered. So, Max voltage of (VLLA-VLLB) should be below 1.391V.

Then HFBurstEntry is related to LL pin voltage as below:

Equation 75.

H F B u r s t E n t r y = \frac{V L L B}{0.55} = 1.818 \cdot V L L B

The LFBurstEntry is always related to LL pin voltage as below:

Equation 76.

L F B u r s t E n t r y = \frac{V L L B}{0.6} = 1.667 \cdot V L L B

For this design, VLLB= 1V and VLLA=(Max voltage of (VLLA-VLLB))-0.1V are considered. By substituting these values in Equation 73, Equation 74, R_LLupper, R_LLlower can be obtained as 641k and 161k respectively.

Finally R_LLupper= 549kΩ and R_LLlower=140kΩ are chosen for this design.

Then final burst entries will be calculated as below.

Equation 77.

V L L B = \frac{140 k \cdot 5}{140 k + 549 k} = 1.016 V

Equation 78.

V L L A = 1.016 V + \frac{140 k \cdot 549 k}{140 k + 549 k} \cdot 10 μ A = 2.131 V

Equation 79.

V L L A - V L L B = 1.116 V

Equation 80.

H F B u r s t E n t r y = 1.818 \cdot 1.016 = 1.847 V

Equation 81.

L F B u r s t E n t r y = 1.667 \cdot 1.016 = 1.693 V